View source for XYY syndrome

{{short description|Genetic condition in which a male has an extra Y chromosome}}
{{distinguish|text=XXY (2 Xs, [[Klinefelter syndrome]])}}
{{Redirect|Xyy|the color model|XyY|the series of novels|The XYY Man|the excessive sense of responsibility|Superman complex}}
{{Infobox medical condition (new)
| name            =
| synonyms        = 47,XYY<ref name=GHR2009/>
| image           = File:Amniocentesis results showing 47, XYY karyotype.png
| alt             =
| caption         = [[Karyotype]] from a male with 47,XYY
| field           = [[Medical genetics]]
| symptoms        = None, being taller than the parents, mildly unusual physical features, severe [[acne]], [[Developmental coordination disorder|poor coordination]], [[Hypotonia|weak muscle tone]], [[learning disability|learning]] and [[Speech disorder|speech problems]]<ref name=GHR2009/><ref name=NORD2012/>
| complications   = 
| onset           = At conception<ref>{{cite web | url=https://www.childrensdayton.org/kidshealth/a/xyy-syndrome | title=XYY Syndrome }}</ref>
| duration        = Lifelong
| types           =
| causes          = Two Y chromosomes in males<ref name=NORD2012/>
| risks           =
| diagnosis       = [[Genetic testing]]<ref name=NORD2012/>
| differential    = [[Klinefelter syndrome]], [[Marfan syndrome]], [[Sotos syndrome]]<ref name=NORD2012/>
| prevention      = None<ref name=GARD2017/>
| treatment       = [[Speech therapy]], [[tutoring]]<ref name=NORD2012/>
| medication      =
| prognosis       = Normal life expectancy<ref name=NORD2012/>
| frequency       = ~1 in 1,000 males<ref name=GHR2009/>
| deaths          =
}}
<!-- Definition and symptoms -->

'''XYY syndrome''', also known as '''Jacobs syndrome''' and '''Superman syndrome''', is an [[Aneuploidy|aneuploid]] [[genetic condition]] in which a male has an extra [[Y chromosome]].<ref name=GHR2009/> There are usually few symptoms.<ref name=NORD2012>{{cite web|url=https://rarediseases.org/rare-diseases/xyy-syndrome/|title=XYY Syndrome|date=2012|website=NORD (National Organization for Rare Disorders)|access-date=11 November 2017}}</ref> These may include being taller than average and an increased risk of [[Learning disability|learning disabilities]].<ref name=GHR2009/><ref name=NORD2012/> The person is generally otherwise normal, including typical rates of [[fertility]].<ref name=GHR2009/>

<!-- Cause and diagnosis -->
The condition is generally not [[heredity|inherited]] but rather occurs as a result of a random event during [[spermatogenesis|sperm development]].<ref name=GHR2009/> Diagnosis is by a [[chromosomal analysis]], but most of those affected are not diagnosed within their lifetime.<ref name=NORD2012/> There are 47 chromosomes, instead of the usual 46, giving a 47,XYY [[karyotype]].<ref name=GHR2009/>

<!-- Treatment and epidemiology -->
Treatment may include [[speech therapy]] or extra help with schoolwork, and outcomes are generally positive.<ref name=NORD2012/> The condition occurs in about 1 in 1,000 male births.<ref name=GHR2009>{{Cite web|url=https://medlineplus.gov/genetics/condition/47xyy-syndrome/|title=47,XYY syndrome|website=Genetics Home Reference|language=en|access-date=2017-03-19|date=January 2009}}</ref> Many people with the condition are unaware that they have it.<ref name=GARD2017>{{cite web|title=47, XYY syndrome|url=https://rarediseases.info.nih.gov/diseases/5674/47-xyy-syndrome|website=Genetic and Rare Diseases Information Center (GARD)|access-date=11 November 2017|language=en|date=2017|archive-date=11 November 2017|archive-url=https://web.archive.org/web/20171111205247/https://rarediseases.info.nih.gov/diseases/5674/47-xyy-syndrome}}</ref> The condition was first described in 1961.<ref>{{cite book|last1=Bostwick|first1=David G.|last2=Cheng|first2=Liang|title=Urologic Surgical Pathology E-Book|date=2014|publisher=Elsevier Health Sciences|isbn=978-0-323-08619-6|page=682|url=https://books.google.com/books?id=wrHQAgAAQBAJ&pg=PA682|language=en}}</ref>

==Signs and symptoms==

===Physical traits===
People with the 47,XYY [[karyotype]] have an increased growth rate from early childhood, with an average final height approximately {{convert |7 |cm |frac=8}} above expected final height.<ref name="Nielsen 1998">{{cite web |author=Nielsen, Johannes|year=1998|title=How is height growth?|url=http://www.aaa.dk/TURNER/ENGELSK/XYY.HTM#height|archive-date=2010-03-07|archive-url=https://web.archive.org/web/20100307091453/http://www.aaa.dk/TURNER/ENGELSK/XYY.HTM#height|work=XYY males. An orientation |publisher=The Turner Center, [[Aarhus]] Psychiatric Hospital, [[Risskov]], Denmark}}</ref> In [[Edinburgh]], Scotland, eight 47,XYY boys born 1967–1972 and identified in a newborn screening programme had an average height of {{convert |188.1 |cm |ftin |abbr=on |frac=8}} at age 18—their fathers' average height was {{convert |174.1 |cm |ftin |abbr=on |frac=8}}, their mothers' average height was {{convert |162.8 |cm |ftin |abbr=on |frac=8}}.<ref name="Gravholt 2013"/><ref name="Ratcliffe 1992">{{cite journal|last1=Ratcliffe|first1=Shirley G.|last2=Pan|first2=Huiqi|last3=McKie|first3=Mark|date=November–December 1992|title=Growth during puberty in the XYY boy|journal=[[Annals of Human Biology]]|volume=19|issue=6|pages=579–587|doi=10.1080/03014469200002392|pmid=1476413}}</ref> The increased gene dosage of three X/Y chromosome [[pseudoautosomal region]] (PAR1) [[short-stature homeobox gene|SHOX]] genes has been postulated as a cause of the increased stature seen in all three sex chromosome trisomies: 47,XXX, 47,XXY, and 47,XYY.<ref name="SHOX">{{cite book |author1=Cohen, Pinchas |author2=Shim, Melanie |year=2007 |chapter=Hyperpituitarism, tall stature, and overgrowth syndromes |editor1=Kliegman, Robert M. |editor2=Behrman, Richard E. |editor3=Jenson, Hal B. |editor4=Stanton, Bonita F. |title=Nelson textbook of pediatrics |edition=18th |location=Philadelphia |publisher=[[Elsevier|Saunders]] |isbn=978-1-4160-2450-7 |pages=2303–2307}} p. 2304: Table 561-1. Differential diagnosis of tall stature and overgrowth syndromes. Postnatal overgrowth leading to childhood tall stature—includes: Klinefelter syndrome (XXY), SHOX excess syndromes, XYY.
* {{cite journal |author1=Kanaka-Gantenbein, Christina |author2=Kitsiou, Sophia |author3=Mavrou, Ariadni |author4=Stamoyannou, Lela |author5=Kolialexi, Aggeliki |author6=Kekou, Kyriaki |author7=Liakopoulou, Magda |author8=Chrousos, George |date=April 2004 |title=Tall stature, insulin resistance, and disturbed behavior in a girl with the triple X syndrome harboring three SHOX genes: offspring of a father with mosaic Klinefelter syndrome but with two maternal X chromosomes |journal=[[Hormone Research (journal)|Horm Res]] |volume=61 |issue=5 |pages=205–210 |doi=10.1159/000076532 |pmid=14752208|s2cid=41958098 }}
* {{cite journal |author1=Aksglaede, Lise |author2=Skakkebaek, Niels E. |author3=Juul, Anders |date=January 2008 |title=Abnormal sex chromosome constitution and longitudinal growth: serum levels of insulin-like growth factor (IGF)-I, IGF binding protein-3, luteinizing hormone, and testosterone in 109 males with 47,XXY, 47,XYY, or sex-determining region of the Y chromosome (SRY)-positive 46,XX karyotypes |journal=[[Journal of Clinical Endocrinology and Metabolism|J Clin Endocrinol Metab]] |volume=93 |issue=1 |pages=169–176 |doi=10.1210/jc.2007-1426 |pmid=17940117 |url=http://jcem.endojournals.org/cgi/reprint/93/1/169.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://jcem.endojournals.org/cgi/reprint/93/1/169.pdf |archive-date=2022-10-09 |url-status=live|doi-access=free }}
* {{cite journal |author1=Tüttelmann, Frank |author2=Gromoll, Jörg |year=2010 |title=Novel genetic aspects of Klinefelter's syndrome |journal=Mol Hum Reprod |volume= 16|issue= 6|pages= 386–95|doi=10.1093/molehr/gaq019 |pmid=20228051|doi-access=free }}</ref>
Severe [[acne vulgaris|acne]] was noted in a very few early case reports, but dermatologists specializing in acne now doubt the existence of a relationship with 47,XYY.<ref name="Plewig 2000">{{cite book |author1=Plewig, Gerd |author2=Kligman, Albert M. |year=2000 |title=Acne and rosacea |edition=3rd |page=377 |location=Philadelphia |publisher=[[Springer Science+Business Media|Springer-Verlag]] |isbn=978-3-540-66751-3}}</ref>

Prenatal [[testosterone]] levels are normal in 47,XYY males.<ref>{{cite journal |author1=Ratcliffe, Shirley G. |author2=Read, Graham |author3=Pan, Huiqi |author4=Fear, Claudine |author5=Lindenbaum, Richard |author6=Crossley, Jennifer |date=September 1994 |title=Prenatal testosterone levels in XXY and XYY males |journal=[[Hormone Research (journal)|Horm Res]] |volume=42 |issue=3 |pages=106–109 |pmid=7995613 |doi=10.1159/000184157}}</ref> Most 47,XYY males have normal sexual development and have normal fertility.<ref name="Gravholt 2013"/><ref name="Milunsky 2010"/><ref name="Gardner 2004">{{cite book |author1=Gardner, R.J. McKinlay |author2=Sutherland, Grant R. |year=2004 |title=Chromosome abnormalities and genetic counseling |edition=3rd |pages=29–30, 42, 199, 207, 257, 263, 393, 424–430 |location=Oxford |publisher=[[Oxford University Press]] |isbn=978-0-19-514960-9 |quote=From early meiotic studies, it was concluded that the extra Y was eliminated before the spermatocyte formed, with an X-Y bivalent usually seen at diakinesis, and more recent studies support this concept. However, FISH analyses of sperm, enabling hundreds of cells to be analyzed, have shown a very small increased faction of 24,YY spermatozoa in the ejaculate of XYY men (Table 12-1). Thus it appears the vast majority of spermatocytes lose the extra Y before entering meiosis, a very few XYY primary spermatocytes are able to slip through and produce YY (and XY) spermatozoa. These cytogenetic findings parallel the observation that XYY men have no ''discernible'' increase in risk to have children with a sex chromosome abnormality. A true increased risk of a fraction of a per cent could be distinguished only with the greatest of difficulty when the background population risk is of a similar order of magnitude. As for the autosomes, no convincing case exists for any increased risk for aneuploidy in the children of men with 47,XYY.<br />To our knowledge, there is no report of a discernibly increased risk for the XYY male to have chromosomally abnormal children. A slight increase in gonosomal imbalances in sperm (Table 12-1) might nevertheless lead some to choose prenatal diagnosis.}}</ref><ref name="Gardner 2012">{{cite book|author1=Gardner, R.J. McKinlay |author2=Sutherland, Grant R. |author3=Shaffer, Lisa G. |year=2012|title=Chromosome abnormalities and genetic counseling|edition=4th|location=Oxford|publisher=[[Oxford University Press]]|isbn=978-0-19-537533-6|pages=9–10, 12, 36, 52, 221, 224, 230, 285–286, 293, 440–441, 477–480, 484|quote=The two other conditions, XXX and XYY, apparently have little effect on fertility; furthermore, they are not discernibly associated with any increased risk for chromosomally abnormal offspring.<br />While the IQ is in the normal range, it is usually lower than those of sibs or controls, and about half of XYY boys have a mild learning difficulty, and may display poor attention and impulsivity in the classroom.}}</ref>

=== Cognitive and behavioral traits ===
In contrast to the other common sex chromosome [[aneuploidies]]—[[Triple X syndrome|47,XXX]] and 47,XXY ([[Klinefelter syndrome]])—the average of the [[IQ]] scores of 47,XYY boys identified by newborn screening programs was not reduced compared to the general population.<ref name="Bender 1986">{{cite book|last1=Bender|first1=Bruce G.|last2=Puck|first2=Mary H.|last3=Salbenblatt|first3=James A.|last4=Robinson|first4=Arthur|year=1986|chapter=Cognitive development of children with sex chromosome abnormalities|editor-last=Smith|editor-first=Shelley D.|title=Genetics and learning disabilities|location=San Diego|publisher=College-Hill Press|pages=[https://archive.org/details/geneticslearning0000unse/page/175 175–201]|isbn=978-0-88744-141-7|quote=Figure 8-3. Estimated full-scale IQ distributions for SCA and control children: 47,XXX (mean ~83), 45,X & Variant (mean ~85), 47,XXY (mean ~95), 47,XYY (mean ~100), Controls and SCA Mosaics (mean ~104)|chapter-url=https://archive.org/details/geneticslearning0000unse/page/175}}</ref><ref name="Leggett 2010">{{cite journal|last1=Leggett|first1=Victoria|last2=Jacobs|first2=Patricia|last3=Nation|first3=Kate|last4=Scerif|first4=Gaia|last5=Bishop|first5=Dorothy V. M.|date=February 2010|title=Neurocognitive outcomes of individuals with a sex chromosome trisomy: XXX, XYY, or XXY: a systematic review|journal=[[Dev Med Child Neurol]]|volume=52|issue=2|pages=119–129|doi=10.1111/j.1469-8749.2009.03545.x|pmc=2820350|pmid=20059514|quote=Males with XYY have average IQs, consistent with the one study showing normal brain volume on magnetic resonance imaging. In contrast, both XXY and XXX groups tend to have below-average verbal IQ and small cerebral volume.}}</ref> In a summary of six prospective studies of 47,XYY boys identified by newborn screening programmes, twenty-eight 47,XYY boys had an average 100.76 [[verbal IQ]], 108.79 [[performance IQ]], and 105.00 [[full-scale IQ]].<ref name="Netley 1986">{{cite book|author=Netley, Charles T.|year=1986|chapter=Summary overview of behavioural development in individuals with neo-natally identified X and Y aneuploidy|editor1=Ratcliffe, Shirley G. |editor2=Paul, Natalie |title=Prospective studies on children with sex chromosome aneuploidy|series=Birth defects original article series '''22''' (3)|pages=293–306|location=New York|publisher=[[John Wiley & Sons|Alan R. Liss]]|isbn=978-0-8451-1062-1}}</ref> In a [[systematic review]] including two prospective studies of 47,XYY boys identified by newborn screening programs and one retrospective study of 47,XYY men identified by screening men over {{convert |184 |cm |ftin |abbr=on |frac=8}} in height, forty-two 47,XYY boys and men had an average 99.5 verbal IQ and 106.4 performance IQ.<ref name="Leggett 2010"/><ref name="Ratcliffe 1994">{{cite book|last=Ratcliffe|first=Shirley G.|year=1994|chapter=The psychological and psychiatric consequences of sex chromosome abnormalities in children, based on population studies|editor-last=Poustka|editor-first=Fritz |title=Basic approaches to genetic and molecularbiological developmental psychiatry|location=Berlin|publisher=[[Quintessenz]]|pages=99–122|isbn=978-3-86128-209-9|quote=19 XYY boys: average verbal IQ=100.2 (range 66–121), average performance IQ=104.3 (range 83–131), average full-scale IQ=102.3; 86 XY control boys matched by the 1970 Registrar General's Classification of Social Class based on their father's occupation: average full-scale IQ=116.1;<br />15 XYY boys with siblings: average verbal IQ=104.0, average performance IQ=106.7; siblings of XYY boys: average verbal IQ=112.9, average performance IQ=114.6.}}</ref><ref name="Walzer 1991">{{cite book|last1=Walzer|first1=Stanley|last2=Bashir|first2=Anthony S|last3=Silbert|first3=Annette R.|year=1991|chapter=Cognitive and behavioral factors in the learning disabilities of 47,XXY and 47,XYY boys|editor1-last=Evans|editor1-first=Jane A|editor2-last=Hamerton|editor2-first=John L|editor3-last=Robinson|editor3-first=Arthur |title=Children and young adults with sex chromosome aneuploidy: follow-up, clinical and molecular studies|series=Birth defects original article series '''26''' (4)|pages=45–58|location=New York|publisher=[[John Wiley & Sons|Wiley-Liss]]|isbn=978-0-471-56846-9|quote=11 XYY boys: average verbal IQ=103.96 (range=73–139), average performance IQ=106.64 (range=84–129), average full-scale IQ=105.45 (range=80–138); 9 XY familial balanced autosomal chromosome translocation control boys: average full-scale IQ=119.33 (range=103–137).}}</ref><ref name="Theilgaard 1984">{{cite journal|last=Theilgaard|first=Alice|date=December 1984|title=A psychological study of the personalities of XYY- and XXY-men. Results|journal=[[Acta Psychiatrica Scandinavica|Acta Psychiatr Scand Suppl]]|volume=70|issue=s315|pages=38–49|doi=10.1111/j.1600-0447.1984.tb11065.x|pmid=6595938|s2cid=221445990|quote=12 XYY men over 184 cm tall: average verbal IQ=99.9, average performance IQ=97.8, average full-scale IQ=99.1 (range: 77–124); 12 XY control men over 184 cm tall, matched by age, height, and social class based on their father's occupation: average full-scale IQ=119.4}}</ref>

In prospective studies of 47,XYY boys identified by newborn screening programs, the IQ scores of 47,XYY boys were usually slightly lower than those of their siblings.<ref name="Gravholt 2013"/><ref name="Robinson 1985">{{cite book|last1=Robinson|first1=Arthur|last2=Bender|first2=Bruce G.|last3=Puck|first3=Mary H.|last4=Salbenblatt|first4=James A.|year=1985|chapter=Growth and development of children with a 47,XYY karyotype|editor-last=Sandberg|editor-first=Avery A. |title=The Y chromosome: Part B. Clinical aspects of Y chromosome abnormalities|series=Progress and topics in cytogenetics '''6'''|location=New York|publisher=[[John Wiley & Sons|Alan R. Liss]]|pages=265–275|isbn=978-0-8451-2498-7|oclc=12557546|quote=Follow-up studies on the total unselected group of prepubertal or early pubertal 47,XYY boys are remarkably similar despite different methods of following their progress and different policies of informing the parents. As with other forms of SCA there is great variability in the expression of the genotype. The most consistent findings are height over the 50th percentile, normal IQ usually a little lower than that of sibling controls, delay in speech and language development, and the need for extra help in school.}}</ref> In Edinburgh, fifteen 47,XYY boys with siblings identified in a newborn screening program had an average 104.0 verbal IQ and 106.7 performance IQ, while their siblings had an average 112.9 verbal IQ and 114.6 performance IQ.<ref name="Ratcliffe 1994"/>

Approximately half of 47,XYY boys identified by newborn screening programs had learning difficulties—a higher proportion than found among siblings and above-average-IQ control groups.<ref name="Gravholt 2013"/><ref name="Gardner 2012"/> In Edinburgh, 54% of 47,XYY boys (7 of 13) identified in a newborn screening program received remedial reading teaching compared to 18% (4 of 22) in an above-average-IQ control group of 46,XY boys matched by their father's social class.<ref name="Ratcliffe 1994"/> In [[Boston]], USA 55% of 47,XYY boys (6 of 11) identified in a newborn screening program had learning difficulties and received part-time resource room help compared to 11% (1 of 9) in an above-average-IQ control group of 46,XY boys with familial balanced autosomal [[chromosomal translocation|chromosome translocations]].<ref name="Walzer 1991"/>

Developmental delays and behavioral problems are also found, but these characteristics vary widely among affected boys and men, are not unique to 47,XYY and are managed no differently from in 46,XY males.<ref name="Milunsky 2010"/> Aggression is not seen more frequently in 47,XYY males.<ref name="Gravholt 2013"/><ref name="Milunsky 2010"/>

Patients with XYY syndrome have been shown to have a higher risk of developing certain diseases such as [[asthma]], seizure problems, and tremors. Some 47,XYY patients have been found to have genitourinary malformations. These include cryptorchidism, hypoplastic scrotum, microphallus, and hypospadias.<ref name="Bardsley 2013">{{cite journal |last1=Bardsley |first1=Martha Zeger |last2=Kowal |first2=Karen |last3=Levy |first3=Carly |last4=Gosek |first4=Ania |last5=Ayari |first5=Natalie |last6=Tartaglia |first6=Nicole |last7=Lahlou |first7=Najiba |last8=Winder |first8=Breanna |last9=Grimes |first9=Shannon |last10=Ross |first10=Judith L. |title=47,XYY Syndrome: Clinical Phenotype and Timing of Ascertainment |journal=The Journal of Pediatrics |date=October 2013 |volume=163 |issue=4 |pages=1085–1094 |doi=10.1016/j.jpeds.2013.05.037|pmid=23810129 | pmc=4097881 }}</ref> These men could be diagnosed{{what|date=February 2023}} with infertility as a result of oligospermia or sperm chromosomal abnormalities.<ref name="Milunsky 2010"/> According to certain psychological studies, people with XYY syndrome may have problems with impulse control and emotional regulation.<ref name="Milunsky 2010"/> Increased testosterone levels were found to be correlated with an increased risk of aggressive behavior in incarcerated males with 47,XYY syndrome.<ref name="Bardsley 2013"/> [[File:XYY syndrome.svg|thumb|
Diagram showing XYY syndrome formation. MI and MII are the stages of meiosis, while the blue and pink circles are male (sperm) and female (ovum) cells,  respectively, and the blue and pink bars are Y- and X-chromosomes, respectively.

The purple cell has 2 Y-chromosomes and 1 X-chromosome caused by the ovum fusing with a sperm cell with two Y-chromosomes, which was due to division problems in MII of the male.
]]47,XYY is not inherited; it usually occurs as a random event during the formation of [[Spermatozoon|sperm]] cells. An incident in chromosome separation during anaphase II (of [[meiosis#Meiosis II|meiosis II]]) called [[nondisjunction]] can result in sperm cells with an extra copy of the Y-chromosome. If one of these atypical sperm cells contributes to the genetic makeup of a child, the child will have an extra Y-chromosome in each of the body's cells.<ref name="Robinson 1999">{{cite journal |author1=Robinson, David O. |author2=Jacobs, Patricia A. |date=November 1, 1999 |title=The origin of the extra Y chromosome in males with a 47,XYY karyotype |journal=[[Human Molecular Genetics|Hum Mol Genet]] |volume=8 |issue=12 |pages=2205–2209 |pmid=10545600 |doi=10.1093/hmg/8.12.2205|doi-access=free }}</ref>

In some cases, the extra Y-chromosome results from nondisjunction during [[mitosis]] in early embryonic development. This can produce 46,XY/47,XYY [[Mosaic (genetics)|mosaics]].<ref name="Robinson 1999"/>

==Diagnosis==
47,XYY syndrome is not usually diagnosed until learning issues are present. The syndrome is diagnosed in an increasing number of children prenatally by [[amniocentesis]] and [[chorionic villus sampling]]<ref>{{Cite book|url=https://books.google.com/books?id=99YPDvFWBB0C&pg=PA91|title=NORD Guide to Rare Disorders|author=National Organization for Rare Disorders|date=2003|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-3063-1|page=91|language=en}}</ref> in order to obtain a chromosome karyotype, where the abnormality can be observed.

It is estimated that only 15–20% of children with 47,XYY syndrome are ever diagnosed. Of these, approximately 30% are diagnosed prenatally. For the rest of those diagnosed after birth, around half are diagnosed during childhood or adolescence after developmental delays are observed. The rest are diagnosed after any of a variety of symptoms, including fertility problems (5%)<ref>{{Cite book|url=https://books.google.com/books?id=rDAJ4G_8EIkC&pg=PA586|title=Psychopathology of Childhood and Adolescence: A Neuropsychological Approach|last=Davis|first=Andrew S. |date=2012-12-20|publisher=Springer Publishing Company|isbn=978-0-8261-0928-6|page=586|language=en}}</ref> have been seen.

==Epidemiology==
Around 1 in 1,000 boys are born with a 47,XYY karyotype.<ref name="Gravholt 2013"/><ref name="Milunsky 2010"/> The incidence of 47,XYY is not known to be affected by the parents' ages.<ref name="Gravholt 2013"/><ref name="Milunsky 2010"/>

==History==

===1960s===
In April 1956, ''[[Hereditas]]'' published the discovery by [[cytogenetics|cytogeneticists]] [[Joe Hin Tjio]] and [[Albert Levan]] at [[Lund University]] in [[Sweden]] that the normal number of chromosomes in [[ploidy|diploid]] human cells was 46—not 48, as had been believed for the preceding thirty years.<ref>{{cite journal |doi=10.1111/j.1601-5223.1956.tb03010.x |author1=Tjio, Joe Hin |author2=Levan, Albert |date=April 1956 |title=The chromosome number of man |journal=[[Hereditas]] |volume=42 |issue=1 |pages=1–6|hdl=10261/15776 |doi-access=free }}</ref> In the wake of the establishment of the normal number of human chromosomes, 47,XYY was the last of the common sex chromosome aneuploidies to be discovered, two years after the discoveries of [[Klinefelter syndrome#Cause|47,XXY]],<ref>{{cite journal |author1=Jacobs, Patricia A. |author2=Strong, John A. |date=January 31, 1959 |title=A case of human intersexuality having a possible XXY sex-determining mechanism |journal=[[Nature (journal)|Nature]] |volume=183 |issue=4657 |pages=302–3 |doi= 10.1038/183302a0 |pmid=13632697|bibcode=1959Natur.183..302J |s2cid=38349997 }}</ref> [[Turner syndrome#History|45,X]]<ref>{{cite journal |author=Ford, Charles E. |author2=Jones, Kenneth W. |author3=Polani, Paul E. |author4=de Almeida, José Carlos Cabral |author5=Briggs, John H. |date=April 4, 1959 |title=A sex-chromosome anomaly in a case of gonadal dysgenesis (Turner's syndrome) |journal=[[The Lancet|Lancet]] |volume=273 |issue=7075 |pages=711–3 |doi=10.1016/S0140-6736(59)91893-8 |pmid=13642858}}</ref> and [[Triple X syndrome#First case|47,XXX]]<ref>{{cite journal |author1=Jacobs, Patricia A. |author2=Baikie, Albert G. |author3=Court Brown, W. Michael |author4=MacGregor, Thomas N. |author5=Harnden, David G. |date=September 26, 1959 |title=Evidence for the existence of the human "super female" |journal=[[The Lancet|Lancet]] |volume=274 |issue=7100 |pages=423–5 |doi=10.1016/S0140-6736(59)90415-5 |pmid=14406377}}</ref> in 1959. Even the much less common [[48,XXYY syndrome|48,XXYY]]<ref>{{cite journal |author1=Muldal, Sylfest |author2=Ockey, Charles H. |date=August 27, 1960 |title=The "double male": a new chromosome constitution in Klinefelter's syndrome |journal=[[The Lancet|Lancet]] |volume=276 |issue=7147 |pages=492–3 |doi=10.1016/S0140-6736(60)91624-X}}</ref> had been discovered in 1960, a year before 47,XYY.

Screening for those [[X chromosome]] aneuploidies was possible before the advent of human chromosome analysis by noting the presence or absence of "female" sex chromatin bodies ([[Barr body|Barr bodies]]) in the [[cell nucleus|nuclei]] of [[interphase]] cells in [[Buccal smear#Medical procedure|buccal smears]], a technique developed a decade ''before'' the first reported sex chromosome aneuploidy.<ref name="Barr 1949">{{cite journal |author1=Barr, Murray L. |author2=Bertram, Ewart G. |date=April 30, 1949 |title=A morphological distinction between neurones of the male and female, and the behaviour of the nucleolar satellite during accelerated nucleoprotein synthesis |journal=[[Nature (journal)|Nature]] |volume=163 |issue=4148 |pages=676–677 |doi=10.1038/163676a0 |pmid=18120749 |bibcode=1949Natur.163..676B |s2cid=4093883 }}</ref> An analogous technique to screen for Y-chromosome aneuploidies by noting supernumerary "male" sex chromatin bodies was not developed until 1970, a decade ''after'' the first reported male sex chromosome aneuploidy.<ref name="pursuit 1970">{{cite journal |date=June 6, 1970 |title=In pursuit of the ''Y'' chromosome |journal=[[Nature (journal)|Nature]] |volume=226 |issue=5249 |page=897 |doi=10.1038/226897a0 |pmid=4192294|bibcode=1970Natur.226..897. |s2cid=4169027 |doi-access=free }}
* {{cite journal |date=February 6, 1971 |title=Dyeing the ''Y'' chromosome |journal=[[The Lancet|Lancet]] |volume=297 |issue=7693 |pages=275–276 |doi=10.1016/S0140-6736(71)91008-7}}</ref>

The first published report of a man with a 47,XYY karyotype was by the American cytogeneticist [[Avery Sandberg]] and his colleagues at [[Roswell Park Comprehensive Cancer Center]] (then known as Roswell Park Memorial Institute) in [[Buffalo, New York]] in 1961. It was an incidental finding in a normal 44-year-old, 6&nbsp;ft. [183&nbsp;cm] tall man of average intelligence who was karyotyped because he had a daughter with [[Down syndrome]].<ref name="Sandberg 1961">{{cite journal |author1=Sandberg, Avery A. |author2=Koepf, George F. |author3=Ishihara, Takaaki |author4=Hauschka, Theodore S. |date=August 26, 1961 |title=An XYY human male |journal=[[The Lancet|Lancet]] |volume=278 |issue=7200 |pages=488–489 |pmid=13746118 |doi=10.1016/S0140-6736(61)92459-X}}
* {{cite journal |author1=Hauschka, Theodore S. |author2=Hasson, John E. |author3=Goldstein, Milton N. |author4=Koepf, George F. |author5=Sandberg, Avery A. |date=March 1962 |title=An XYY man with progeny indicating familial tendency to non-disjunction |journal=[[American Journal of Human Genetics|Am J Hum Genet]] |volume=14 |pages=22–30 |pmid=13905424 |pmc=1932182 |issue=1}}</ref> Only a dozen isolated 47,XYY cases were reported in the medical literature in the four years following the first report by Sandberg.<ref name="Court Brown 1968">{{cite journal |last=Court Brown |first=W. Michael |date=December 1968 |title=Males with an XYY sex chromosome complement |journal=[[Journal of Medical Genetics|J Med Genet]]|volume=5 |issue=4 |pages=341–59 |doi=10.1136/jmg.5.4.341 |pmid=4890326 |pmc=1468679}}</ref>

The XYY syndrome, if named after the discoverer, should rightly be termed Sandberg syndrome and not Jacobs syndrome although the British cytogeneticist [[Patricia Jacobs]] did indeed contribute meaningfully to medical knowledge of XYY. In December 1965 and March 1966, ''[[Nature (journal)|Nature]]'' and ''[[The Lancet]]'' published the first preliminary reports by Jacobs and her colleagues at the [[MRC Human Genetics Unit]] at [[Western General Hospital]] in [[Edinburgh]] of a chromosome survey of 315 male patients at [[State Hospital]] in [[Carstairs]], [[Lanarkshire]]—[[Scotland]]'s only special security hospital for [[developmental disability|developmentally disabled]] people —that found nine patients, ages 17 to 36, averaging almost 6&nbsp;ft. in height (avg. 5'11", range: 5'7" to 6'2"), had a 47,XYY karyotype, and mischaracterized them as aggressive and violent criminals.<ref name="Court Brown 1968"/><ref>{{cite journal |author1=Jacobs, Patricia A. |author2=Brunton, Muriel |author3=Melville, Marie M. |author4=Brittain, Robert P. |author5=McClemont, William F. |date=December 25, 1965 |title=Aggressive behavior, mental sub-normality and the XYY male |journal=[[Nature (journal)|Nature]] |volume=208 |issue=5017 |pages=1351–2 |doi=10.1038/2081351a0 |pmid=5870205|bibcode=1965Natur.208.1351J |s2cid=4145850 }}
* {{cite journal |author1=Price, William H. |author2=Strong, John A. |author3=Whatmore, Peter B. |author4=McClemont, William F. |date=March 12, 1966 |title=Criminal patients with XYY sex-chromosome complement |journal=[[The Lancet|Lancet]] |volume=287 |issue=7437 |pages=565–6 |doi=10.1016/S0140-6736(66)90760-4 |pmid=4159988}}
* {{cite journal |author=editorial |date=March 12, 1966 |title=The YY syndrome |journal=[[The Lancet|Lancet]] |volume=287 |issue=7437 |pages=583–4 |doi=10.1016/S0140-6736(66)90771-9 |pmid=4159658}}
* {{cite journal |author1=Price, William H. |author2=Whatmore, Peter B. |date=February 25, 1967 |title=Criminal behavior and the XYY male |journal=[[Nature (journal)|Nature]] |volume=213 |issue=5078 |page=815 |doi= 10.1038/213815a0 |pmid=6031815|bibcode=1967Natur.213..815P |s2cid=4158233 |doi-access=free }}
* {{cite journal |author1=Price, William H. |author2=Whatmore, Peter B. |date=March 4, 1967 |title=Behaviour disorders and pattern of crime among XYY males identified at a maximum security hospital |journal=[[BMJ|Br Med J]] |volume=1 |issue=5539 |pages=533–6 |pmid=6017153 |pmc=1841401 |doi=10.1136/bmj.1.5539.533}}
* {{cite journal |author1=Court Brown, W. Michael |author2=Price, William H. |author3=Jacobs, Patricia A. |date=May 11, 1968 |title=Further information on the identity of 47,XYY males |journal=[[BMJ|Br Med J]] |volume=2 |issue=5601 |pages=325–8 |pmid=5689727 |pmc=1985597 |doi=10.1136/bmj.2.354.325-a}}
* {{cite journal |author1=Jacobs, Patricia A. |author2=Price, William H. |author3=Court Brown, W. Michael |author4=Brittain, Robert P. |author5=Whatmore, Peter B. |date=May 1968 |title=Chromosome studies on men in a maximum security hospital |journal=[[Annals of Human Genetics]] |volume=31 |issue=4 |pages=339–58 |url=http://www3.interscience.wiley.com/cgi-bin/fulltext/119911478/PDFSTART |doi=10.1111/j.1469-1809.1968.tb00566.x |s2cid=83969793 |url-access=subscription }}{{Dead link|date=May 2023 |bot=InternetArchiveBot |fix-attempted=yes }}
* {{cite journal |author1=Court Brown, W. Michael |author2=Price, William H. |author3=Jacobs, Patricia A. |date=November 23, 1968 |title=The XYY male |journal=[[BMJ|Br Med J]] |volume=4 |issue=5629 |page=513 |url=http://www.bmj.com/cgi/pdf_extract/4/5629/513-a |doi=10.1136/bmj.4.5629.513-a |s2cid=62593088 |url-access=subscription }}
* {{cite journal |author=Jacobs, Patricia A. |date=September 1982 |title=The William Allan Memorial Award address: human population cytogenetics: the first twenty-five years |journal=[[American Journal of Human Genetics|Am J Hum Genet]]|volume=34 |issue=5 |pages=689–98 |pmid=6751075 |pmc=1685430}}
* {{cite book |author=Harper, Peter S. |year=2006 |chapter=The sex chromosomes |title=First years of human chromosomes: the beginnings of human cytogenetics |location=Bloxham |publisher=Scion |isbn=978-1-904842-24-8 |pages=77–96}}</ref><ref name="Green 1985">{{cite book |author=Green, Jeremy |year=1985 |chapter=Media sensationalism and science: The case of the criminal chromosome |pages=[https://archive.org/details/expositoryscienc0000unse/page/139 139–161] |editor1=Shinn, Terry |editor2=Whitley, Richard |title=Expository science: Forms and functions of popularisation |isbn=978-90-277-1831-0 |publisher=[[D. Reidel|D. Reidel Pub. Co.]] |location=Dordrecht, Holland |chapter-url=https://archive.org/details/expositoryscienc0000unse/page/139 }}</ref><ref name="Beckwith 2002">{{cite book |author=Beckwith, Jonathan R. |year=2002 |chapter=The myth of the criminal chromosome |title=Making genes, making waves: A social activist in science |chapter-url=https://archive.org/details/makinggenesmakin0000beck |chapter-url-access=registration |location=Cambridge, Mass. |publisher=[[Harvard University Press]] |isbn=978-0-674-00928-8 |pages=[https://archive.org/details/makinggenesmakin0000beck/page/116 116–134]}}</ref> Over the next decade, almost all published XYY studies were on height-selected, institutionalized XYY males.<ref name="Milunsky 2010"/>

In January 1968 and March 1968, ''[[The Lancet]]'' and ''[[Science (journal)|Science]]'' published the first U.S. reports of tall, institutionalized XYY males by Mary Telfer, a [[biochemist]], and colleagues at the [[Elwyn Inc.|Elwyn Institute]].<ref name="Telfer 1968a">{{cite journal |author1=Telfer, Mary A. |author2=Baker, David |author3=Longtin, Lucien |date=January 13, 1968 |title=YY syndrome in an American Negro |journal=[[The Lancet|Lancet]] |volume=291 |issue=7533 |page=95 |doi=10.1016/S0140-6736(68)90107-4 |pmid=4169701}}
* {{cite journal |author1=Telfer, Mary A. |author2=Baker, David |author3=Clark, Gerald R. |author4=Richardson, Claude E. |date=March 15, 1968 |title=Incidence of gross chromosomal errors among tall criminal American males |journal=[[Science (journal)|Science]] |volume=159 |issue=3820 |pages=1249–50 |doi=10.1126/science.159.3820.1249 |jstor=1723887 |pmid=5715587|bibcode=1968Sci...159.1249T |s2cid=27416349 }}</ref> Telfer found five tall, developmentally disabled XYY boys and men in hospitals and penal institutions in [[Pennsylvania]], and since four of the five had at least moderate facial [[acne vulgaris|acne]], reached the erroneous conclusion that acne was a defining characteristic of XYY males.<ref name="Telfer 1968a"/> After learning that convicted mass murderer [[Richard Speck]] had been karyotyped, Telfer not only incorrectly assumed the acne-scarred Speck was XYY, but reached the false conclusion that Speck was the [[archetype|archetypical]] XYY male—or "supermale" as Telfer referred to XYY males outside of peer-reviewed scientific journals.<ref>{{cite journal |author=Telfer, Mary A. |date=November–December 1968 |title=Are some criminals born that way? |journal=Think |volume=34 |issue=6 |pages=24–8 |issn=0040-6112}}{{blockquote|Why do men commit crimes of violence? For some, the urge to violence may be inborn—traced to something called the Y chromosome...<br />Once in every 500 male births, for example, the sex chromosome complement is XXY rather than XY, thus erring in the direction of femaleness. The resulting individual, called a Klinefelter male, is usually retarded, unusually tall and sterile.<br />Erring in the other direction, however, is the XYY complement resulting in the "supermale." He is also unusually tall and somewhat retarded, but appears to be highly, perhaps too highly, sexually motivated...<br />We were intrigued by Dr. Jacobs' contention that an extra Y chromosome results in tall stature, mild mental retardation, and severely disordered personality characterized by violent, aggressive behavior. We therefore planned to confirm and extend her studies.<br /><br />''Syndrome Status for the XYY''<br />The XXY male has long been thought to display a constellation of symptoms that makes him diagnosable; that is, he has achieved syndrome status. It would seem that the XYY male is fast achieving similar status. His symptoms, as we and other laboratories tend to think of them, are: extremely tall stature, long limbs and strikingly long arm span, facial acne, mild mental retardation, severe mental illness (including psychosis) and aggressive, antisocial behavior with a long history of arrests, frequently beginning at an early age.<br />On reading newspaper accounts of Richard Speck, who murdered eight Chicago student nurses in 1966, we noted all these traits and therefore concluded that Speck was a likely candidate for the XYY disorder. Independently, a cytogenetic laboratory in Chicago confirmed this hunch, reinforcing our inclination to believe that the XYY syndrome is really coming of age. It seems quite possible that in the XYY male, exemplified by Speck, biologists are describing in genetic terms a certain type of defective criminal who has long been explicitly recognized by the forensic psychiatrist.}}</ref>

In April 1968, ''[[The New York Times]]''—using Telfer as a main source—introduced the XYY genetic condition to the general public in a three-part series on consecutive days that began with a Sunday front-page story about the planned use of the condition as a mitigating factor in two murder trials in [[Paris]]<ref name="Daniel Hugon">Daniel Hugon, Paris, France
* {{cite news |author=Garrison, Lloyd |date=October 15, 1968 |title=French murder jury rejects chromosome defect as defense |newspaper=[[The New York Times]] |page=5 |url=https://www.nytimes.com/1968/10/15/archives/french-murder-jury-rejects-chromosome-defect-as-defense.html }}
* {{cite magazine |date=October 25, 1968 |title=Criminal law: Question of Y |magazine=[[Time (magazine)|Time]] |volume=92 |issue=17 |page=76 |url=http://www.time.com/time/magazine/article/0,9171,900408,00.html |access-date=April 21, 2010 |archive-date=June 24, 2013 |archive-url=https://web.archive.org/web/20130624143935/http://www.time.com/time/magazine/article/0,9171,900408,00.html }}</ref> and [[Melbourne]]<ref name="Lawrence Hannell">Lawrence Hannell, Melbourne, Australia
* {{cite news |date=October 10, 1968 |title=Extra chromosome brings acquittal on murder charge |newspaper=[[The New York Times]] |page=94 |url=https://www.nytimes.com/1968/10/10/archives/extra-chromosome-brings-an-acquittal-on-murder-charge.html }}
* {{cite news |author=Auerbach, Stuart |date=October 10, 1968 |title=Genetic abnormality is basis for acquittal |newspaper=[[The Washington Post]] |page=A1 |url=https://pqasb.pqarchiver.com/washingtonpost_historical/access/185091562.html?FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=October 26, 2012 |archive-url=https://web.archive.org/web/20121026113916/http://pqasb.pqarchiver.com/washingtonpost_historical/access/185091562.html?FMT=ABS&FMTS=ABS:AI }}
* {{cite news |author=Getze, George |date=February 3, 1969 |title=Australia precedent for XYY syndrome case held dubious |newspaper=[[Los Angeles Times]] |page=C1 |url=https://pqasb.pqarchiver.com/latimes/access/673351452.html?FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=January 31, 2013 |archive-url=https://archive.today/20130131173103/http://pqasb.pqarchiver.com/latimes/access/673351452.html?FMT=ABS&FMTS=ABS:AI }} An Australian murder case that was reported to have been decided on the basis of the so-called XYY syndrome actually was not concerned with chromosome counts at all.</ref>—and falsely reported that Richard Speck was an XYY male and that the condition would be used in an appeal of his murder conviction.<ref name="Green 1985"/><ref name="Lyons 1968">{{cite news |author=Lyons, Richard D. |date=April 21, 1968 |title=Genetic abnormality is linked to crime; Genetics linked to violent crimes |newspaper=[[The New York Times]] |page=1 |url=https://www.nytimes.com/1968/04/21/archives/genetic-abnormality-is-linked-to-crime-genetics-linked-to-violent.html }}
* {{cite news |author=Lyons, Richard D. |date=April 22, 1968 |title=Ultimate Speck appeal may cite a genetic defect |newspaper=[[The New York Times]] |page=43 |url=https://www.nytimes.com/1968/04/22/archives/ultimate-speck-appeal-may-cite-a-genetic-defect.html }}
* {{cite news |author=Lyons, Richard D. |date=April 23, 1968 |title=Chromosome test for flaws costly; 2 scientists cite scarcity of skilled aides for analyses |newspaper=[[The New York Times]] |page=27 |url=https://www.nytimes.com/1968/04/23/archives/chromosome-test-for-flaws-costly-2-scientists-cite-scarcity-of.html }}
* {{cite news |author=editorial |date=April 23, 1968 |title=Nature or nurture? |newspaper=[[The New York Times]] |page=46 |url=https://www.nytimes.com/1968/04/23/archives/nature-or-nurture.html }}
* {{cite news |date=April 23, 1968 |title=Geneticist: Didn't test Speck |newspaper=[[Chicago Sun-Times]] |page=8}}{{blockquote|Dr. Pergament said he and Dr. Sato, a research fellow, had absolutely no connection with the Speck case and never examined Speck. The report was also denied by Speck's attorney, Public Defender Gerald W. Getty. "I never knew those doctors existed before I read about them in the paper," Getty said. Getty did say that a chromosomal test was performed on Speck, before Speck's trial, by a geneticist from outside the Chicago area. He declined to identify the geneticist, and he said the results of the test never have been disclosed. "It was agreed," he said, "that the results would not be disclosed unless I wished them disclosed. And I still don't." In any case, Getty said, the results could not be used in an appeal—since they were not part of the trial evidence. If anything, he said, they could only be used in connection with a new trial.}}
* {{cite news |date=November 26, 1968 |title=Getty tells Speck case plea basis; 10 issues are raised regarding trial |newspaper=[[Chicago Tribune]] |page=A16 |url=https://pqasb.pqarchiver.com/chicagotribune/access/586226742.html?dids=586226742:586226742&FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=October 19, 2012 |archive-url=https://web.archive.org/web/20121019192904/http://pqasb.pqarchiver.com/chicagotribune/access/586226742.html?dids=586226742:586226742&FMT=ABS&FMTS=ABS:AI }}{{blockquote|At the same time he made public reports from Vanderbilt University showing no abnormal makeup of Speck's chromosomes...<br />Getty displayed a letter of Sept. 26, 1966, relating that photographic evidence of 18 cells from Speck's blood showed no chromosome abnormality. He also exhibited a letter of last July 3, indicating that 100 of 101 cells in a sample of Speck's blood studied after the original tests showed the normal 46 chromosomes. The other cell had 45, regarded by the Vanderbilt investigators as having no significance.}}
* {{cite journal |author=Engel, Eric |date=September 1972 |title=The making of an XYY |journal=[[American Association on Intellectual and Developmental Disabilities|Am J Ment Defic]]|volume=77 |issue=2 |pages=123–7 |pmid=5081078}}—article by [[Vanderbilt University]] endocrinologist and geneticist Eric Engel, who performed two confidential chromosome analyses of Speck in September 1966 and June 1968. Based on mischaracterizations of XYY males as aggressive and violent criminals in the December 1965 and March 1966 preliminary reports by Jacobs, et al., Engel had made an unsolicited request in August 1966 to Speck's appointed defense attorney, [[Cook County Public Defender]] Gerald W. Getty, to confidentially karyotype Speck—which was repeated after false news reports in April 1968 that Speck was XYY.</ref> The series was echoed the following week by articles—again using Telfer as a main source—in ''[[Time (magazine)|Time]]'' and ''[[Newsweek]]'',<ref>{{cite magazine |date=May 3, 1968 |title=Of chromosomes & crime |magazine=[[Time (magazine)|Time]] |volume=91 |issue=18 |page=41 |url=http://www.time.com/time/magazine/article/0,9171,841254,00.html|archive-url=https://web.archive.org/web/20101029122601/http://www.time.com/time/magazine/article/0,9171,841254,00.html|archive-date=October 29, 2010}}
* {{cite magazine |date=May 6, 1968 |title=Born bad? |magazine=[[Newsweek]] |volume=76 |issue=19 |page=87}}</ref> and six months later in ''[[The New York Times Magazine]]''.<ref>{{cite news |author=Stock, Robert W. |date=October 20, 1968 |title=The XYY and the criminal |newspaper=[[The New York Times Magazine]] |page=SM30 |url=https://www.nytimes.com/1968/10/20/archives/the-xyy-and-the-criminal-the-xyy-and-the-criminal.html}}</ref>

In December 1968, the ''[[Journal of Medical Genetics]]'' published the first XYY review article—by Willam Michael Court Brown (1918–1969),<ref>The first XYY review article, by W. Michael Court Brown, a physician and world authority on [[radiation biology]] and cytogenetics, was published in December 1968. Court Brown had established the MRC Clinical Effects of Radiation Unit at [[Western General Hospital]] in [[Edinburgh]] in 1956, which was renamed the MRC Clinical and Population Cytogenetics Unit in 1967 (and subsequently renamed the [[MRC Human Genetics Unit]] in 1988). In 1962, Court Brown had been the first to suggest—based on findings of antisocial behavior in some institutionalized [[Klinefelter syndrome]] (47,XXY) patients and psychosis in some institutionalized [[Triple X syndrome]] (47,XXX) patients—that individuals with sex chromosome abnormalities could be held in law to suffer from diminished responsibility.
* {{cite journal |last=Court Brown |first=W. Michael |date=September 8, 1962 |title=Sex chromosomes and the law |journal=[[The Lancet|Lancet]] |volume=280 |issue=7254 |pages=508–509 |doi=10.1016/S0140-6736(62)90378-1}}
* {{cite journal |date=January 4, 1969 |title=William Michael Court Brown |journal=[[The Lancet|Lancet]] |volume=293 |issue=7584 |pages=57–58 |doi=10.1016/S0140-6736(69)91029-0 |pmid=4178806}}
* {{cite journal |author=Harnden, David G. |date=March 1969 |title=W.M. Court Brown |journal=[[Journal of Medical Genetics|J Med Genet]] |volume=6 |issue=1 |pages=107–108 |doi=10.1136/jmg.6.1.107 |pmid=4890463 |pmc=1468708}}
* {{cite book |author=Hsu, T. C. |year=1979 |title=Human and mammalian cytogenetics: an historical perspective |location=New York |publisher=[[Springer Science+Business Media|Springer-Verlag]] |isbn=978-0-387-90364-4 |pages=[https://archive.org/details/humanmammaliancy0000hsut/page/41 41–42] |url=https://archive.org/details/humanmammaliancy0000hsut/page/41 }}</ref> director of the MRC Human Genetics Unit—which reported that he had found no overrepresentation of XYY males in nationwide chromosome surveys of prisons and hospitals for developmentally disabled and mentally ill people in Scotland, and concluded that studies confined to institutionalized XYY males may be guilty of [[selection bias]], and that long-term [[longitudinal study|longitudinal]] [[prospective cohort study|prospective]] studies of newborn XYY boys were needed.<ref name="Court Brown 1968"/>

In May 1969, at the annual meeting of the [[American Psychiatric Association]], Telfer and her Elwyn Institute colleagues reported that case studies of the institutionalized XYY and XXY males they had found convinced them that XYY males had been falsely stigmatized and that their behavior may not be significantly different from chromosomally normal 46,XY males.<ref>{{cite news |agency=Associated Press |date=May 6, 1969 |title=A kind word said for the XYY men; Psychiatrist cites evidence many are good citizens |newspaper=[[The New York Times]] |page=93 |url=https://www.nytimes.com/1969/05/06/archives/a-kind-word-said-for-the-xyy-men-psychiatrist-cites-evidence-many-a.html }}
* {{cite journal |author1=Clark, Gerald R. |author2=Telfer, Mary A. |author3=Baker, David |author4=Rosen, Marvin |date=May 1970 |title=Sex chromosomes, crime, and psychosis |journal=[[American Journal of Psychiatry|Am J Psychiatry]] |volume=126 |issue=11 |pages=1659–63 |url=http://ajp.psychiatryonline.org/cgi/content/abstract/126/11/1659 |pmid=5443650 |doi=10.1176/ajp.126.11.1659 |access-date=2010-04-16 |archive-date=2011-06-12 |archive-url=https://web.archive.org/web/20110612031407/http://ajp.psychiatryonline.org/cgi/content/abstract/126/11/1659 |url-access=subscription }}
* {{cite journal |author1=Baker, David |author2=Telfer, Mary A. |author3=Richardson, Claude E. |author4=Clark, Gerald R. |date=November 2, 1970 |title=Chromosome errors in men with antisocial behavior. Comparison of selected men with Klinefelter syndrome and XYY chromosome pattern |journal=[[Journal of the American Medical Association|JAMA]] |volume=214 |issue=5 |pages=869–78 |pmid=4248395 |url=http://jama.ama-assn.org/cgi/content/abstract/214/5/869 |doi=10.1001/jama.214.5.869 |url-access=subscription }}</ref>

In June 1969, the [[National Institute of Mental Health]] (NIMH) Center for Studies of Crime and Delinquency held a two-day XYY conference in [[Chevy Chase, Maryland]].<ref>{{cite book |author=Shah, Saleem A. |year=1970 |title=Report on the XYY chromosomal abnormality |location=Chevy Chase, Md. |publisher=[[National Institute of Mental Health|NIMH]] Center for Studies of Crime and Delinquency |series=Public Health Service publication No. 2103 |oclc=235264}} June 19–20, 1969 XYY conference.</ref> In December 1969, with a grant from the NIMH Center for Studies of Crime and Delinquency, cytogeneticist Digamber Borgaonkar at [[Johns Hopkins Hospital]] began a chromosome survey of (predominantly African-American) boys ages 8 to 18 in all [[Maryland]] institutions for delinquent, neglected, or mentally ill juveniles, which was suspended from February–May 1970 due to an [[American Civil Liberties Union]] (ACLU) lawsuit regarding the study's lack of [[informed consent]].<ref name="Pyeritz 1977">{{cite book |author1=Pyeritz, Reed |author2=Schreier, Herb |author3=Madansky, Chuck |author4=Miller, Larry |author5=Beckwith, Jon |year=1977 |chapter=The XYY male: The making of a myth |editor=Ann Arbor Science for the Peopleial Collective |title=Biology as a social weapon |pages=86–100 |location=Minneapolis |publisher=Burgess Pub. Co |isbn=978-0-8087-4534-1}}</ref><ref>{{cite news |agency=Associated Press |date=December 27, 1969 |title=Gene abnormality set for Md. study |newspaper=[[The Washington Post]] |page=B7 |url=https://pqasb.pqarchiver.com/washingtonpost_historical/access/149109532.html?FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=October 26, 2012 |archive-url=https://web.archive.org/web/20121026103520/http://pqasb.pqarchiver.com/washingtonpost_historical/access/149109532.html?FMT=ABS&FMTS=ABS:AI }}
* {{cite news |author=Bauer, Diane |date=January 22, 1970 |title=Maryland tests for criminal potential |newspaper=[[The Washington Daily News]] |page=7}} reprinted in Katz (1972). ''Experimentation with human beings'', pp. 342–343.
* {{cite news |author=Cohen, Richard M. |date=February 7, 1970 |title=Genetic study is opposed |newspaper=[[The Washington Post]] |page=B2 |url=https://pqasb.pqarchiver.com/washingtonpost_historical/access/158044782.html?FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=October 26, 2012 |archive-url=https://web.archive.org/web/20121026103532/http://pqasb.pqarchiver.com/washingtonpost_historical/access/158044782.html?FMT=ABS&FMTS=ABS:AI }}
* {{cite news |author=Bauer, Diane |date=February 13, 1970 |title=XYY tests stop |newspaper=[[The Washington Daily News]] |page=5}} reprinted in Katz (1972). ''Experimentation with human beings'', pp. 343–344.
* {{cite news |author=Bauer, Diane |date=May 4, 1970 |title=Criminal-prone tests resumed |newspaper=[[The Washington Daily News]] |page=1}} reprinted in Katz (1972). ''Experimentation with human beings'', p. 344.
* {{cite magazine |date=May 18, 1970 |title=Congenital criminals? |magazine=[[Newsweek]] |volume=75 |issue=20 |pages=98–99}}
* {{cite book |author1=Katz, Jay |author2=Capron, Alexander Morgan |author3=Glass, Eleanor Swift |year=1972 |title=Experimentation with human beings; the authority of the investigator, subject, professions, and state in the human experimentation process |url=https://archive.org/details/experimentationw0000katz |url-access=registration |pages=[https://archive.org/details/experimentationw0000katz/page/342 342–346] |location=New York |publisher=[[Russell Sage Foundation]] |isbn=978-0-87154-438-4 }}
* {{cite book |author1=Borgaonkar, Diagamber S. |author2=Shah, Saleem A. |year=1974 |chapter=The XYY chromosome male—or syndrome? |pages=135–222 |editor1=Steinberg, Arthur Gerald |editor2=Bearn, Alexander G. |title=Progress in medical genetics. Volume 10 |location=New York |publisher=Grune & Stratton |isbn=978-0-8089-0841-8}}
* {{cite book |author=Borgaonkar, Diagamber S. |year=1978 |chapter=Cytogenic screening of community-dwelling males |pages=[https://archive.org/details/geneticissuesinp00cohe/page/215 215–234] |editor1=Cohen, Bernice H. |editor2=Lilienfield, Abraham M. |editor3=Huang, P. C. |title=Genetic issues in public health and medicine |location=Springfield, Ill. |publisher=Charles C Thomas |isbn=978-0-398-03659-1 |chapter-url=https://archive.org/details/geneticissuesinp00cohe/page/215 }}
* {{cite book |author=Washington, Harriet A. |year=2004 |chapter=Born for evil? Stereotyping the karyotype: A case history in the genetics of aggressiveness |editor1=Roelcke, Volker |editor2=Maio, Giovanni |title=Twentieth century ethics of human subjects research: historical perspectives on values, practices, and regulations |pages=319–334 |location=Stuttgart |publisher=[[Franz Steiner Verlag]] |isbn=978-3-515-08455-0}}
* {{cite book |author=Washington, Harriet A. |year=2006 |chapter=The children's crusade: research targets young African Americans |title=Medical apartheid: the dark history of experimentation on black Americans from colonial times to the present |pages=[https://archive.org/details/medicalapartheid00wash/page/279 279–283] |location=New York |publisher=[[Doubleday (publisher)|Doubleday]] |isbn=978-0-385-50993-0 |chapter-url=https://archive.org/details/medicalapartheid00wash/page/279 }}</ref>

In the late 1960s and early 1970s, screening of consecutive newborns for sex chromosome abnormalities was undertaken at seven centers worldwide: in [[Denver]] (Jan 1964–1974), [[Edinburgh]] (Apr 1967–Jun 1979), [[New Haven]] (Oct 1967–Sep 1968), [[Toronto]] (Oct 1967–Sep 1971), [[Aarhus]] (Oct 1969–Jan 1974, Oct 1980–Jan 1989), [[Winnipeg]] (Feb 1970–Sep 1973), and [[Boston]] (Apr 1970–Nov 1974).<ref name="March of Dimes">{{cite book |editor1=Robinson, Arthur |editor2=Lubs, Herbert A. |editor3=Bergsma, Daniel |year=1979 |title=Sex chromosome aneuploidy: prospective studies on children|series=Birth defects original article series '''15''' (1) |location=New York |publisher=[[John Wiley & Sons|Alan R. Liss]] |isbn=978-0-8451-1024-9}}
* {{cite book |editor=Stewart, Donald A. |year=1982 |title=Children with sex chromosome aneuploidy: follow-up studies |series=Birth defects original article series '''18''' (4) |location=New York |publisher=[[John Wiley & Sons|Alan R. Liss]] |isbn=978-0-8451-1052-2}}
* {{cite book |editor1=Ratcliffe, Shirley G. |editor2=Paul, Natalie |year=1986 |title=Prospective studies on children with sex chromosome aneuploidy |series=Birth defects original article series '''22''' (3) |location=New York |publisher=[[John Wiley & Sons|Alan R. Liss]] |isbn=978-0-8451-1062-1}}
* {{cite book |editor1=Evans, Jane A. |editor2=Hamerton, John L. |editor3=Robinson, Arthur |year=1991 |title=Children and young adults with sex chromosome aneuploidy: follow-up, clinical and molecular studies |series=Birth defects original article series '''26''' (4) |location=New York |publisher=[[John Wiley & Sons|Wiley-Liss]] |isbn=978-0-471-56846-9}}</ref> The Boston study, led by [[Harvard Medical School]] child psychiatrist Stanley Walzer at [[Children's Hospital Boston|Children's Hospital]], was unique among the seven newborn screening studies in that it only screened newborn ''boys'' (non-private-ward newborn boys at the [[Brigham and Women's Hospital|Boston Hospital for Women]]) and was funded in part by grants from the NIMH Center for Studies of Crime and Delinquency.<ref name="Boston">{{cite journal |author1=Beckwith, Jon |author2=King, Jonathan |date=November 1974 |title=The XYY syndrome: a dangerous myth |journal=[[New Scientist]] |volume=64 |issue=923 |pages=474–476 |pmid=11664346 |url=https://books.google.com/books?id=XAU4aZVrYv4C&pg=PA474 |access-date=2015-07-02 |archive-date=2023-01-11 |archive-url=https://web.archive.org/web/20230111211926/https://books.google.com/books?id=XAU4aZVrYv4C&pg=PA474 }}
* {{cite news |author=Brody, Jane E. |date=November 15, 1974 |title=Scientists' group terms Boston study of children with extra sex chromosome unethical and harmful |newspaper=[[The New York Times]] |page=93 |url=https://www.nytimes.com/1974/11/15/archives/scientists-group-terms-boston-study-of-children-with-extra-sex.html }}
* {{cite news |author=Knox, Richard |date=November 16, 1974 |title=Scientists oppose survey of chromosome disorder |newspaper=[[The Boston Globe]] |page=3 |url=https://pqasb.pqarchiver.com/boston/access/1975367112.html?FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=January 31, 2013 |archive-url=https://archive.today/20130131135410/http://pqasb.pqarchiver.com/boston/access/1975367112.html?FMT=ABS&FMTS=ABS:AI }}
* {{cite journal |author=Culliton, Barbara J. |date=November 22, 1974 |title=Patients' rights: Harvard is site of battle over X and Y chromosomes |journal=[[Science (journal)|Science]] |volume=186 |issue=4165 |pages=715–717 |doi=10.1126/science.186.4165.715 |jstor=1739961 |pmid= 11643569|bibcode=1974Sci...186..715C }}
* {{cite news |author=Brody, Jane E. |date=December 14, 1974 |title=Harvard backs genetic study; research involving young with XYY chromosome had been criticized |newspaper=[[The New York Times]] |page=20 |url=https://www.nytimes.com/1974/12/14/archives/harvard-backs-genetic-study-research-involving-young-with-xyy.html }}
* {{cite news |author=Bruzelius, Nils |date=December 15, 1974 |title=Harvard Medical School panel rejects plea to end gene study |newspaper=[[The Boston Globe]] |page=8 |url=https://pqasb.pqarchiver.com/boston/access/2056634312.html?FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=January 31, 2013 |archive-url=https://archive.today/20130131215841/http://pqasb.pqarchiver.com/boston/access/2056634312.html?FMT=ABS&FMTS=ABS:AI }}
* {{cite journal |author=Culliton, Barbara J. |date=December 27, 1974 |title=Briefing: Harvard faculty says XYY study should continue |journal=[[Science (journal)|Science]] |volume=186 |issue=4170 |pages=1188–1189 |doi=10.1126/science.186.4170.1189-b |jstor=1739250| pmid=17833922}}
* {{cite journal |author1=Beckwith, Jon |author2=Elseviers, Dirk |author3=Gorni, Luigi |author4=Mandansky, Chuck |author5=Csonka, Leslie |author6=King, Jonathan |date=January 31, 1975 |title=Harvard XYY study |journal=[[Science (journal)|Science]] |volume=187 |issue=4174 |doi=10.1126/science.11643259 |pmid=11643259 |pages=298–9|bibcode=1975Sci...187..298B }}
* {{cite news|date=March 15, 1975|title=Harvard vote backs child behavior study|newspaper=[[The Boston Globe]]|page=7|url=https://pqasb.pqarchiver.com/boston/access/1974822802.html?FMT=CITE&FMTS=CITE:AI|quote=The Harvard Medical School faculty voted last night 199–35, to allow continuation of studies at Children's Hospital Medical Center and at Boston Hospital for Women on children with an extra sex chromosome.|access-date=July 7, 2017|archive-date=January 31, 2013|archive-url=https://archive.today/20130131155148/http://pqasb.pqarchiver.com/boston/access/1974822802.html?FMT=CITE&FMTS=CITE:AI}}
* {{cite news |author=Brody, Jane E. |date=June 20, 1975 |title=Babies' screening is ended in Boston; extra chromosome study stirred controversy on its ethics and value |newspaper=[[The New York Times]] |page=6 |url=https://www.nytimes.com/1975/06/20/archives/babies-screening-is-ended-in-boston-extra-chromosome-study-stirred.html |quote=Dr. Walzer said that when he stopped screening on the study's fifth anniversary in April,... }}
* {{cite journal |author=Culliton, Barbara J. |date=June 27, 1975 |title=XYY: Harvard researcher under fire stops newborn screening |journal=[[Science (journal)|Science]] |volume=188 |issue=4195 |pages=1284–1285 |doi=10.1126/science.11643276 |jstor=1741001 |pmid=11643276|bibcode=1975Sci...188.1284C }}
* {{cite news|author=Knox, Richard|date=July 6, 1975|title=XYY battle is over, research ethic war isn't|newspaper=[[The Boston Globe]]|page=A4|url=https://pqasb.pqarchiver.com/boston/access/2024063982.html?FMT=ABS&FMTS=ABS:AI|quote=In May...Walzer nevertheless decided to cut short his XYY screening by about eight months.|access-date=July 7, 2017|archive-date=January 31, 2013|archive-url=https://archive.today/20130131165145/http://pqasb.pqarchiver.com/boston/access/2024063982.html?FMT=ABS&FMTS=ABS:AI}}
* {{cite news |author=Weiss, Philip |date=September 15, 1975 |title=Ending the test for extra chromosomes |newspaper=[[The Harvard Crimson]] |url=http://www.thecrimson.com/article/1975/9/15/ending-the-test-for-extra-chromosomes/ }}
* {{cite journal |last1=Bauer |first1=Diane |last2=Bayer |first2=Ronald |last3=Beckwith |first3=Jonathan |last4=Bermant |first4=Gordon |last5=Borgaonkar |first5=Digamber S. |last6=Callahan |first6=Daniel |last7=Caplan |first7=Arthur |last8=Conrad |first8=John |last9=Culver |first9=Charles M. |last10=Dworkin |first10=Gerald |last11=Edgar |first11=Harold |last12=Gaylin |first12=Willard |last13=Gerald |first13=Park |last14=Harris |first14=Clarence |last15=King |first15=Johnathan |last16=Macklin |first16=Ruth |last17=Mazur |first17=Allan |last18=Michels |first18=Robert |last19=Mone |first19=Carola |last20=Petchesky |first20=Rosalind |author20-link=Rosalind Petchesky |last21=Powledge |first21=Tabitha M. |last22=Pyeritz |first22=Reed E. |last23=Robinson |first23=Arthur |last24=Scanlon |first24=Thomas |last25=Shah |first25=Saleem A. |last26=Shannon |first26=Thomas A. |last27=Steinfels |first27=Margaret |last28=Swazey |first28=Judith P. |last29=Wachtel |first29=Paul |last30=Walzer |first30=Stanley |date=August 1980 |title=The XYY controversy: researching violence and genetics |journal=[[Hastings Center Report|Hastings Cent Rep]] |volume=10 |issue=4 |pages=Suppl 1–32 |pmid=7399889 |jstor=3560454 |quote=Stanley Walzer: On the issue of informed consent prior to newborn chromosome screening, Science for the People proved correct. They had predicted that the amount of information that had to be shared prior to screening was so extensive and complex that true informed consent was impossible to obtain ''at that point''.<br />Arthur Robinson: When we stopped in 1974, we had done 40,000 analyses. From an epidemiological point of view, I would have preferred to have done 80,000... Why did we stop? Well, in the first place there was the informed consent problem. When we started in 1964 feelings about informed consent were very different. Try to imagine how one would go about getting truly informed consent from 40,000 people. With the implications of what we would find, in a sex chromosome variation, it would be an almost impossible task. That's one reason why we stopped.|doi=10.2307/3560454 }}</ref>  The Edinburgh study was led by [[Shirley Ratcliffe]] who focused her career on it and published the results in 1999.<ref name=BMJobit>{{cite journal|last1=Sapietis|first1=Una|last2=Butler|first2=Gary|title=Obituary: Shirley Ratcliffe|journal=BMJ|date=21 July 2014|volume=349|article-number=g4716|doi=10.1136/bmj.g4716|s2cid=220108224}}</ref><ref name=WellcomeArchives>{{cite web|title=Archive record: Dr Shirley Ratcliffe and the Edinburgh MRC Clinical and Population Cytogenetics Unit Study of Long Term Outcomes for Children Born with Sex Chromosome Abnormalities|url=http://archives.wellcome.ac.uk/DServe/dserve.exe?dsqIni=Dserve.ini&dsqApp=Archive&dsqCmd=Show.tcl&dsqDb=Catalog&dsqSearch=(AltRefNo=%27pp/sra%27)&dsqPos=0|publisher=Wellcome Library Western Manuscripts and Archives catalogue|access-date=27 February 2018|language=en}}</ref>

===1970s===
In December 1969, Lore Zech at the [[Karolinska Institutet|Karolinska Institute]] in Stockholm first reported intense [[fluorescence]] of the [[Adenine|A]] [[Thymine|T]]-rich distal half of the long arm of the Y chromosome in the nuclei of [[metaphase]] cells treated with [[quinacrine]] mustard.<ref name="Zech 1969">{{cite journal |author=Zech, Lore |date=December 1969 |title=Investigation of metaphase chromosomes with DNA-binding flurochromes |journal=[[Experimental Cell Research|Exp Cell Res]] |volume=58 |issue=2–3 |page=463 |doi = 10.1016/0014-4827(69)90531-X }}</ref> In April 1970, Peter Pearson and [[Martin Bobrow]] at the [[Medical Research Council (UK)|MRC]] Population Genetics Unit in [[Oxford]] and Canino Vosa at the [[University of Oxford]] reported fluorescent "male" sex chromatin bodies in the nuclei of interphase cells in buccal smears treated with quinacrine dihydrochloride, which could be used to screen for Y chromosome aneuploidies like 47,XYY.<ref name="Pearson 1970">{{cite journal |author1=Pearson, Peter L. |author2=Bobrow, Martin |author3=Vosa, Canio G. |date=April 4, 1970 |title=Technique for identifying ''Y'' chromosomes in human interphase nuclei |journal=[[Nature (journal)|Nature]] |volume=226 |issue=5240 |pages=78–80 |pmid=4190810 |doi=10.1038/226078a0|bibcode=1970Natur.226...78P |s2cid=4013867 }}
* {{cite news|author=Knox, Richard|date=August 14, 1970|title=Test may lead to choice in baby's sex|newspaper=[[The Boston Globe]]|page=26|url=https://pqasb.pqarchiver.com/boston/access/1946618622.html?FMT=ABS&FMTS=ABS:AI|access-date=July 7, 2017|archive-date=February 1, 2013|archive-url=https://archive.today/20130201075818/http://pqasb.pqarchiver.com/boston/access/1946618622.html?FMT=ABS&FMTS=ABS:AI}}</ref>

In December 1970, at the annual meeting of the [[American Association for the Advancement of Science]] (AAAS), its retiring president, geneticist [[H. Bentley Glass]], cheered by the legalization of abortion in [[New York (state)|New York]],<ref>
{{cite news |author=Kovach, Bill |date=April 11, 1970 |title=Final approval of abortion bill voted in Albany; Rockefeller to sign it over weekend despite appeal by Cooke for veto |newspaper=[[The New York Times]] |page=1 |url=https://www.nytimes.com/1970/04/11/archives/final-approval-of-abortion-bill-voted-in-albany-rockefeller-to-sign.html}}
* {{cite news |author=Kihss, Peter |date=July 2, 1970 |title=Abortions begun in state under liberal new law; Scores get abortions under new law |newspaper=[[The New York Times]] |page=1 |url=https://select.nytimes.com/gst/abstract.html?res=FB0F1FFC385C1B7493C0A9178CD85F448785F9}}</ref> envisioned a future where pregnant women would be required by the government to abort XYY "sex deviants".<ref name="Pyeritz 1977"/><ref>
{{cite news |author=Sullivan, Walter |date=December 29, 1970 |title=Growth to slow down, association head says |newspaper=[[The New York Times]] |page=14 |url=https://www.nytimes.com/1970/12/29/archives/growth-to-slow-down-association-head-says.html}}
* {{cite journal |author=Glass, Bentley |date=January 8, 1971 |title=Science: endless horizons or golden age? |journal=[[Science (journal)|Science]] |volume=171 |issue=3966 |pages=23–29 |doi=10.1126/science.171.3966.23 |jstor=1731074 |pmid=17737984|bibcode=1971Sci...171...23G }}
* {{cite journal |author=Glass, Bentley |date=April 9, 1971 |title=Reply to: Less than golden future |journal=[[Science (journal)|Science]] |volume=172 |issue=3979 |pages=111–112 |doi=10.1126/science.172.3979.111-c |jstor=1730891 |pmid=17735208}}
* {{cite journal |author=Glass, Bentley |date=July 9, 1971 |title=Reply to: What price the perfect baby? |journal=[[Science (journal)|Science]] |volume=173 |issue=3992 |pages=103–104 |jstor=1732191 |pmid=5104145 |doi=10.1126/science.173.3992.103-c }}</ref> Mischaracterization of the XYY genetic condition was quickly incorporated into high school biology textbooks<ref name="Pyeritz 1977"/><ref name="Modern Biology 1973">{{cite book |author1=Otto, James Howard |author2=Towle, Albert |year=1973 |title=Modern biology |location=New York |publisher=Holt, Rinehart and Winston |isbn=978-0-03-091337-2 |page=[https://archive.org/details/modernbiology00otto/page/185 185] |quote=Another abnormal condition results when a normal X-bearing egg is fertilized by a YY sperm, formed by non-disjunction during spermatogenesis. This produces an XYY male who is usually over six feet in height and very aggressive. |url=https://archive.org/details/modernbiology00otto/page/185 }}</ref> and medical school psychiatry textbooks,<ref name="Pyeritz 1977"/><ref name="Sadock Synopsis">{{cite book |author1=Freedman, Alfred M. |author2=Kaplan, Harold I. |author3=Sadock, Benjamin J. |year=1972 |title=Modern Synopsis of Comprehensive Textbook of Psychiatry |edition=1st |location=Baltimore |publisher=Williams & Wilkins |oclc=1232929 |page=711 |quote=Figure 43.2}}
* {{cite book |author1=Sadock, Benjamin James |author2=Sadock, Virginia Alcott |year=2007 |title=Kaplan and Sadock's Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry |edition=10th |location=Philadelphia |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-7327-0 |page=154 |quote=A famous case of an "XYY" insanity defense is illustrated in Figure 4.4–1. Richard Speck. He was convicted in 1966 of slaying eight nurses in Chicago by stabbing and strangulation. His legal defense was based on his genetic makeup, which was "XYY". Individuals with these genes have been reported to be tall, mentally retarded, have acne, and show aggressive behavior... (Courtesy of Wide World Photos.)}}</ref> where misinformation still persists decades later.<ref name="Beckwith 2002"/>

In 1973, child psychiatrist Herbert Schreier at Children's Hospital told Harvard Medical School microbiologist [[Jon Beckwith]] of [[Science for the People]] that he thought Walzer's Boston XYY study was unethical; Science for the People investigated the study and, regarding the study, filed an ethics complaint with Harvard Medical School in March 1974.<ref name="Beckwith 2002"/> In November 1974, Science for the People went public with their objections to the Boston XYY study in a press conference and a ''[[New Scientist]]'' article alleging inadequate informed consent, a lack of benefit (since no specific treatment was available) but substantial risk (by stigmatization with a false stereotype) to the subjects, and that the unblinded experimental design could not produce meaningful results regarding the subjects' behavior.<ref name="Boston"/> In December 1974, the Harvard Standing Committee on Medical Research issued a report supporting the Boston XYY study, and in March 1975, the faculty voted 199–35 to allow continuation of the study.<ref name="Boston"/> After April 1975, screening of newborns was discontinued—changes to informed consent procedures and pressure from additional advocacy groups, including the [[Children's Defense Fund]], having led to the discontinuation of the last active U.S. newborn screening programs for sex chromosome abnormalities in Boston and Denver.<ref name="Boston"/>

In a paper published in ''[[New Scientist]]'' on November 14, 1974 entitled "XYY syndrome: a dangerous myth" found no link was found between having an extra Y chromosome and violent behavior. According to the paper, adolescents found to have an extra Y chromosome in a [[Maryland]] institution were [[chemical sterilization|chemically sterilized]] to attempt to maintain "normal behavior," despite this the paper found no major behavioral differences between XY and XYY individuals.<ref>{{Cite web|url=https://www.ojp.gov/ncjrs/virtual-library/abstracts/xyy-syndrome-dangerous-myth|title=XYY SYNDROME - A DANGEROUS MYTH &#124; Office of Justice Programs|website=www.ojp.gov}}</ref>

In August 1976, ''Science'' published a [[retrospective cohort study]] by [[Educational Testing Service]] psychologist [[Herman Witkin]] and colleagues that screened the tallest 16% of men (over 184&nbsp;cm (6'0") in height) born in [[Copenhagen]] from 1944 to 1947 for XXY and XYY karyotypes, and found an increased rate of minor criminal convictions for property crimes among sixteen XXY and twelve XYY men may be related to the lower intelligence of those with criminal convictions, but found no evidence that XXY or XYY men were inclined to be aggressive or violent.<ref name="Witkin 1976">{{cite journal |last1=Witkin |first1=Herman A. |last2=Mednick |first2=Sarnoff A. |last3=Schulsinger |first3=Fini |last4=Bakkestrøm |first4=Eskild |last5=Christiansen |first5=Karl O. |last6=Goodenough |first6=Donald R. |last7=Hirschhorn |first7=Kurt |last8=Lundsteen |first8=Claes |last9=Owen |first9=David R. |last10=Philip |first10=John |last11=Rubin |first11=Donald B. |last12=Stocking |first12=Martha |date=August 13, 1976 |title=Criminality in XYY and XXY men |journal=[[Science (journal)|Science]] |volume=193 |issue=4253 |pages=547–555 |doi=10.1126/science.959813 |jstor=1742747 |pmid=959813|bibcode=1976Sci...193..547W }}
* {{cite news |author=Knox, Richard |date=August 11, 1976 |title=Males with extra chromosomes not violence-prone, Danish study shows |newspaper=[[The Boston Globe]] |page=5 |url=https://pqasb.pqarchiver.com/boston/access/1976214812.html?FMT=ABS&FMTS=ABS:AI |access-date=July 7, 2017 |archive-date=January 31, 2013 |archive-url=https://archive.today/20130131200106/http://pqasb.pqarchiver.com/boston/access/1976214812.html?FMT=ABS&FMTS=ABS:AI }}
* {{cite magazine |date=August 14, 1976 |title=XYY: No link to aggressive crime |magazine=[[Science News|Sci News]] |volume=110 |issue=7 |page=103 |jstor=3961261}}
* {{cite magazine |date=August 30, 1976 |title=Medicine: Capsules |magazine=[[Time (magazine)|Time]] |volume=108 |issue=9 |page=58 |url=http://www.time.com/time/magazine/article/0,9171,918265,00.html |access-date=February 8, 2012 |archive-date=August 14, 2013 |archive-url=https://web.archive.org/web/20130814015954/http://www.time.com/time/magazine/article/0,9171,918265,00.html }}
* {{cite news |author=Brody, Jane E. |date=September 12, 1976 |title=A chromosome link to crime is doubted; Study in Denmark finds no data to back view that 'XYY' men are inclined to be violent |newspaper=[[The New York Times]] |page=18 |url=https://select.nytimes.com/gst/abstract.html?res=FB0F12FE3F5E1A7493C0A81782D85F428785F9 }}</ref>

===1980s and later===
The [[March of Dimes]] sponsored five international conferences in June 1974, November 1977, May 1981, June 1984, and June 1989 and published articles from the conferences in book form in 1979, 1982, 1986, and 1991 from seven longitudinal [[prospective cohort study|prospective cohort studies]] on the development of over 300 children and young adults with sex chromosome abnormalities identified in the screening of almost 200,000 consecutive births in hospitals in Denver, Edinburgh, New Haven, Toronto, Aarhus, Winnipeg, and Boston from 1964 to 1975.<ref name="March of Dimes"/><ref>The five March of Dimes international conferences and four books also included reports on the findings of longitudinal prospective studies in [[London, Ontario]] and [[Tokyo]] on the development of children and with sex chromosome abnormalities identified in part by newborn screening programs.</ref> These seven studies—the only unbiased studies of unselected individuals with sex chromosome abnormalities—have replaced the older, biased studies of institutionalized individuals in understanding the development of individuals with sex chromosome abnormalities.<ref name="Milunsky 2010"/><ref>The last active longitudinal prospective study ended in 2000 with the end of the 36-year Denver study following the death of pediatrician and geneticist Arthur Robinson.
* {{cite book |author1=Robinson, Arthur |author2=Linden, Mary G. |author3=Bender, Bruce G. |year=1998 |chapter=Prenatal diagnosis of sex chromosome abnormalities |pages=249–285 |editor=Milunsky, Aubrey |title=Genetic disorders and the fetus: diagnosis, prevention and treatment |edition=4th |location=Baltimore |publisher=[[Johns Hopkins University Press]] |isbn=978-0-8018-5801-7}}
* {{cite journal |date=May–June 2001 |title=Life adaptation in 35 adults with sex chromosome abnormalities |journal=[[American College of Medical Genetics|Genet Med]] |volume=3 |issue=3 |pages=187–191 |pmid=11388759 |author1=Bender, Bruce G. |author2=Linden, Mary G. |author3=Harmon, Robert J. |doi=10.1097/00125817-200105000-00007|doi-access=free }}</ref>

In May 1997, ''[[Nature Genetics]]'' published the discovery by Ercole Rao and colleagues of the X/Y chromosome [[pseudoautosomal region]] (PAR1) [[short-stature homeobox gene|SHOX]] gene, [[haploinsufficiency]] of which leads to short stature in [[Turner syndrome]] (45,X).<ref name="Rao 1997">{{cite journal |last1=Rao |first1=Ercole |last2=Weiss |first2=Birgit |last3=Fukami |first3=Maki |last4=Rump |first4=Andreas |last5=Niesler |first5=Beate |last6=Mertz |first6=Annelyse |last7=Muroya |first7=Koji |last8=Binder |first8=Gerhard |last9=Kirsch |first9=Stefan |last10=Winkelmann |first10=Martina |last11=Nordsiek |first11=Gabriele |last12=Heinrich |first12=Udo |last13=Breuning |first13=Martijn H. |last14=Ranke |first14=Michael B. |last15=Rosenthal |first15=André |last16=Ogata |first16=Tsutomu |last17=Rappold |first17=Gudrun A. |date=May 1997 |title=Pseudoautosomal deletions encompassing a novel homeobox gene cause growth failure in idiopathic short stature and Turner syndrome |journal=[[Nature Genetics|Nat Genet]] |volume=16 |issue=1 |pages=54–63 |doi=10.1038/ng0597-54 |pmid=9140395|s2cid=26248561 }}</ref> It was subsequently postulated that the increased gene dosage of three SHOX genes leads to tall stature in the sex chromosome trisomies 47,XXX, 47,XXY, and 47,XYY.<ref name="SHOX"/>

In July 1999, ''[[Psychological Medicine]]'' published a [[case-control study]] by [[Royal Edinburgh Hospital]] psychiatrist Michael Götz and colleagues that found an increased rate of criminal convictions among seventeen XYY men identified in the Edinburgh newborn screening study compared to an above-average-IQ control group of sixty XY men, which multiple [[logistic regression]] analysis indicated was mediated mainly through lowered intelligence.<ref name="Götz 1999">
{{cite journal |last1=Götz |first1=Michael J. |last2=Johnstone |first2=Eve C. |last3=Ratcliffe |first3=Shirley G. |date=July 1999 |title=Criminality and antisocial behaviour in unselected men with sex chromosome abnormalities |journal=[[Psychological Medicine|Psychol Med]] |volume=29 |issue=4 |pages=953–962 |doi=10.1017/S0033291799008594 |pmid=10473322|s2cid=23208917 }}</ref>

In June 2002, the ''[[American Journal of Medical Genetics]]'' published results from a longitudinal prospective cohort Denver Family Development Study led by pediatrician and geneticist Arthur Robinson,<ref name="Robinson 1990">{{cite journal |author=Robinson, Arthur |date=April 1990 |title=Living history: an autobiography of Arthur Robinson |journal=[[American Journal of Medical Genetics|Am J Med Genet]] |volume=35 |issue=4 |pages=475–480 |doi=10.1002/ajmg.1320350406 |pmid=2185631}}</ref> which found that in fourteen [[prenatal diagnosis|prenatally diagnosed]] 47,XYY boys (from high [[socioeconomic status]] families), IQ scores available for six boys ranged from 100 to 147 with a mean of 120.<ref name="Linden 2002">{{cite journal |author1=Linden, Mary G. |author2=Bender, Bruce G. |date=June 1, 2002 |title=Fifty-one prenatally diagnosed children and adolescents with sex chromosome abnormalities |journal=[[American Journal of Medical Genetics|Am J Med Genet]] |volume=110 |issue=1 |pages=11–18 |pmid=12116265 |doi=10.1002/ajmg.10394}}</ref> For the eleven of fourteen boys with siblings, in nine instances their siblings were stronger academically, but in one case the subject was performing equal to, and in another case superior to, his siblings.<ref name="Linden 2002"/>

==Society and culture==
Some medical geneticists question whether the term "[[syndrome]]" is appropriate for this condition<ref name="Gravholt 2013">{{cite book |last=Gravholt |first=Claus Højbjerg |year=2013 |chapter=Sex chromosome abnormalities |editor1-last=Pyeritz |editor1-first=Reed E. |editor2-last=Rimoin |editor2-first=David L. |editor3-last=Korf |editor3-first=Bruce R. |title=Emery and Rimoin's principles and practice of medical genetics |edition=6th |pages=1180–1211 |location=San Diego |publisher=[[Academic Press|Elsevier Academic Press]] |isbn=978-0-12-383834-6 |quote=This sex chromosome aneuploidy is not characterized by distinct physical features and, because there does not appear to be recognizable pattern of neurodevelopment or behavioral characteristics, the use of the term ''syndrome'' may be inappropriate. Males with an extra Y chromosome are phenotypically normal and most never come to medical attention.<br />Pubertal development, testicular histology, and spermatogenesis are most often normal.<br />…it appears that XY pairing and recombination occur normally in 47,XYY, the extra Y chromosome being lost during spermatogenesis, so that many XYY men have fathered chromosomally normal children. It has generally been observed that reproductive risks for males with 47,XYY are no higher than for euploid males, despite the fact that ''in situ'' hybridization studies demonstrated a lower frequency of single Y-bearing sperm than expected and a variably higher rate of disomic XX, XY and YY spermatozoa in males with 47,XYY.<br />Population-based studies have demonstrated that intellectual abilities tend to be slightly lower than those of siblings and matched controls and that boys with an extra Y chromosome are more likely to require educational help. However, intelligence is usually well within the normal range.<br />During school age, learning disabilities requiring educational intervention are present in approximately 50% and are as responsive to therapy as they are in children with normal chromosomes. Expressive and receptive language delays and reading disorders are common.}}</ref> because many people with this karyotype appear normal.<ref name="Gravholt 2013"/><ref name="Milunsky 2010">{{cite book |author=Milunsky, Jeff M. |year=2010 |chapter=Prenatal diagnosis of sex chromosome abnormalities |pages=273–312 |editor1=Milunsky, Aubrey |editor2=Milunsky, Jeff M. |title=Genetic disorders and the fetus: diagnosis, prevention and treatment |edition=6th |location=Oxford |publisher=[[Wiley-Blackwell]] |isbn=978-1-4051-9087-9|quote=The addition of a Y chromosome to a normal male chromosome constitution does not produce a discernible phenotype. Males with 47,XYY cannot be characterized by discriminating physical or behavioral features. The first diagnosis of this condition, therefore, was a karyotypic and not a phenotypic discovery.<br />Pubertal development is normal and these men are usually fertile.}}</ref>

=== In popular culture ===

In June 1970, ''[[The XYY Man]]'' was published—the first of seven [[Kenneth Royce]] spy novels whose fictional tall, intelligent, nonviolent XYY hero was a reformed expert [[cat burglar]] recruited by British intelligence for dangerous assignments—and later adapted into a thirteen-episode British summer television series broadcast in 1976 and 1977.<ref>{{cite book |author=Royce, Kenneth |date=June 1, 1970 |title=The XYY Man |location=London |publisher=[[Hodder & Stoughton]] |isbn=978-0-340-10694-5}}
* {{cite news |author=Kneeland, Harold |date=December 8, 1970 |title=Books: Antiheroes and villains |newspaper=[[The Washington Post]] |page=B6 |url=https://pqasb.pqarchiver.com/washingtonpost_historical/access/158533992.html?FMT=ABS&FMTS=ABS:AI |quote=The genetic fable is ''The XYY Man'' by Kenneth Royce (David McKay, $4.95). It leans so lightly on the theory that an extra Y chromosome produces a criminal that the reader can forget the biology and enjoy the fast footwork. Royce has simply manufactured a super cat burglar who is [[eucher]]ed into working for MI6. This tall (that chromosome), intelligent (that chromosome again), functionally nonviolent (that chromosome still again) fellow plays the damndest game with British internal security that ever filled a dossier... |access-date=July 7, 2017 |archive-date=October 26, 2012 |archive-url=https://web.archive.org/web/20121026103543/http://pqasb.pqarchiver.com/washingtonpost_historical/access/158533992.html?FMT=ABS&FMTS=ABS:AI }}</ref><ref name="joseph1980">{{Cite book |last=Joseph |first=Michael |url=https://archive.org/details/25yearsonitv0000unse/page/239/mode/1up?view=theater |title=25 Years on ITV |publisher=Independent Television Books Ltd |year=1980 |isbn=0 900727 81 0 |location=London |page=239 |access-date=2025-07-19}}</ref>

In other fictional television works, a January 1971 episode "By the Pricking of My Thumbs ..." of the British science fiction TV series ''[[Doomwatch]]'' featured an XYY boy expelled from school because his genetic condition led him to be falsely accused of nearly blinding another boy.<ref name="By the Pricking of My Thumbs ...">{{cite book |author1=Fulton, Roger |author2=Betancourt, John |year=1998 |chapter=Doomwatch |title=The Sci-Fi Channel encyclopedia of TV science fiction |location=New York |publisher=[[Hachette Book Group USA|Aspect]] |isbn=978-0-446-67478-2|page=170}} By the Pricking of My Thumbs ... written by Robin Chapman. Sixteen-year-old Stephen Franklin is expelled from school because, his father says, he has an obscure genetic defect—an extra "Y" chromosome.</ref> A November 1993 episode of the American police procedural TV series ''[[Law & Order]]'', "Born Bad", portrays a 14-year-old XYY sociopathic murderer.<ref name="Born Bad">{{cite news |author=Roush, Matt |date=November 17, 1993 |title=Critic's corner |newspaper=[[USA Today]] |page=12D |url=https://pqasb.pqarchiver.com/USAToday/access/55220486.html?FMT=ABS&FMTS=ABS:FT |access-date=July 7, 2017 |archive-date=October 26, 2012 |archive-url=https://web.archive.org/web/20121026113939/http://pqasb.pqarchiver.com/USAToday/access/55220486.html?FMT=ABS&FMTS=ABS:FT }} One of TV's most consistently rewarding series takes a grim and unforgettable detour into the bleak mindset of a teen-age sociopathic murderer. Is society to blame, or as his lawyer argues, is he genetically predisposed to violence, with an extra "Y" chromosome? … the boy's hopeless future seems all too evident.</ref> The May 2007 season finale episode, "Born To Kill", of the American police procedural TV series ''[[CSI: Miami]]'' depicts a 34-year-old XYY [[serial killer]].<ref name="Born To Kill">{{cite journal |author=Hochman, David |date=May 7–13, 2007 |title=Horatio hunts a natural-born killer |journal=[[TV Guide]] |volume=55 |issue=19 |pages=34–36}} There's nothing funny about the season finale. That episode is about a serial killer with "criminal" genes. "It's a real-life natural-born killer situation", executive producer Ann Donahue says. "Usually girls have XX chromosomes and boys have XY, but this killer is XYY, which means too much testosterone." Among other niceties, the killer who has ties to Boston… brands his female victims with the letter Y.</ref>

The false stereotype of XYY boys and men as violent criminals has also been used as a [[plot device]] in the [[horror film]]s ''Il gatto a nove code'' in February 1971 (dubbed into English as ''[[The Cat o' Nine Tails]]'' in May 1971) and ''[[Alien 3]]'' in May 1992.<ref name="Green 1985"/><ref name="Beckwith 2002"/> The main character of the 2005 film ''[[Neo Ned]]'' is a [[neo-nazi]] who has an extra Y chromosome.<ref>{{cite AV media |people=dir. Van Fischer |date=2005 |title=[[Neo Ned]] |trans-title= |type= film|language=en |url= |time=10m00s|location= |publisher= |id= |isbn= |oclc= |quote= }}

</ref>

==See also==
* [[Sex chromosome anomalies]]
* [[Klinefelter syndrome]]
* [[XXYY syndrome]]
* [[XYYY syndrome]]
* [[XYYYY syndrome]]
* [[Turner syndrome]]
* [[Trisomy X]]

==References==
{{reflist}}

== External links ==
{{Commons}}
* Nielsen, Johannes (1998). [https://web.archive.org/web/20100307091453/http://www.aaa.dk/TURNER/ENGELSK/XYY.HTM XYY males. An orientation].
{{Medical resources
| DiseasesDB      = 33038
| ICD10           = {{ICD10|Q|98|5|q|90}}
| ICD9            = {{ICD9|758.8}}
| ICDO            =
| OMIM            =
| MedlinePlus     =
| eMedicineSubj   =
| eMedicineTopic  =
| MeshID          = D014997
| Orphanet        = 8
| SNOMED CT       = 50749006
}}

{{Chromosomal abnormalities}}

{{Authority control}}

{{DEFAULTSORT:Xyy Syndrome}}
[[Category:Sex chromosome aneuploidies]]
[[Category:Y chromosome]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Rare syndromes]]
[[Category:1961 neologisms]]