View source for Ichthyosis

{{Short description|Family of disorders causing dry, thickened, scaly skin}}
{{Infobox medical condition (new)
| name            = Ichthyosis
| synonyms        = Ichthyoses
| image           = Ichthyosis (1).jpg
| caption         = Ichthyosis is characterized by generalised scaly skin.
| field           = [[Dermatology]]
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'''Ichthyosis'''<ref>{{Cite journal |last1=Dorf |first1=Inger LH |last2=Schmidt |first2=Sigrún AJ |last3=Sommerlund |first3=Mette |last4=Koppelhus |first4=Uffe |date=November 2021 |title=Validity of First-Time Diagnoses of Darier's Disease in the Danish National Patient Registry |journal=Clinical Epidemiology |volume= 13 |pages=1063–1069 |doi=10.2147/clep.s326518 |issn=1179-1349|doi-access=free |pmid=34795531 |pmc=8594618 }}</ref> is a family of [[genetic disorder|genetic]] [[skin disorder]]s characterized by [[Xeroderma|dry]], [[Scleroderma|thickened]], scaly skin.<ref name=Andrew2020>{{cite book |last1=James |first1=William D. |last2=Elston |first2=Dirk |last3=Treat |first3=James R. |last4=Rosenbach |first4=Misha A. |last5=Neuhaus |first5=Isaac |title=Andrews' Diseases of the Skin: Clinical Dermatology |date=2020 |publisher=Elsevier |location=Edinburgh |isbn=978-0-323-54753-6 |pages=563–565 |edition=13th |chapter-url=https://books.google.com/books?id=UEaEDwAAQBAJ&pg=PA563 |language=en |chapter=27. Genodermatoses and congenital anomalies }}</ref> The more than 20 types of ichthyosis range in severity of symptoms, outward appearance, underlying genetic cause and mode of inheritance (e.g., [[Dominance (genetics)|dominant, recessive]], [[autosomal]] or [[X-linked]]). Ichthyosis comes {{ety|el|''ἰχθύς'' (ichthys)|fish}}, since dry, scaly skin is the defining feature of all forms of ichthyosis.<ref>{{cite web|url=http://www.hopkinsmedicine.org/health_information_library/index.html?ArticleID=19366|title=Ichthyosis|publisher=Johns Hopkins Medicine|website=Health Information Library|archive-url=https://web.archive.org/web/20090202114600/http://www.hopkinsmedicine.org/health_information_library/index.html?ArticleID=19366|archive-date=2 February 2009}}</ref>

The severity of symptoms can vary enormously, from the mildest, most common, types such as [[ichthyosis vulgaris]], which may be mistaken for normal dry skin, up to life-threatening conditions such as [[harlequin-type ichthyosis]].  Ichthyosis vulgaris accounts for more than 95% of cases.<ref name=Okulicz2003>{{cite journal |vauthors=Okulicz JF, Schwartz RA | year = 2003 | title = Hereditary and acquired ichthyosis vulgaris | journal = International Journal of Dermatology | volume = 42 | issue = 2 | pages = 95–8 | pmid = 12708996 | doi = 10.1046/j.1365-4362.2003.01308.x | s2cid = 20029085 }}</ref>

==Types==
Many types of ichthyoses exist, and an exact diagnosis may be difficult. Types of ichthyoses are classified by their appearance, if they are syndromic or not, and by mode of inheritance.<ref name=":0" /> For example, non-syndromic ichthyoses that are inherited recessively come under the umbrella term autosomal recessive congenital ichthyosis (ARCI).

Ichthyosis caused by mutations in the same gene can vary considerably in severity and symptoms. Some ichthyoses do not appear to fit exactly into any one type while mutations in different genes can produce ichthyoses with similar symptoms. Of note, X-linked ichthyosis is associated with [[Kallmann syndrome]] (close to the [[KAL1 gene|''KAL1'' gene]]). The most common or well-known types are:<ref name=":0">{{Cite journal|last1=Oji|first1=Vinzenz|last2=Preil|first2=Marie-Luise|last3=Kleinow|first3=Barbara|last4=Wehr|first4=Geske|last5=Fischer|first5=Judith|last6=Hennies|first6=Hans Christian|last7=Hausser|first7=Ingrid|last8=Breitkreutz|first8=Dirk|last9=Aufenvenne|first9=Karin|last10=Stieler|first10=Karola|last11=Tantcheva-Poór|first11=Illiana|date=2017|title=S1 guidelines for the diagnosis and treatment of ichthyoses - update|journal=JDDG: Journal der Deutschen Dermatologischen Gesellschaft|language=en|volume=15|issue=10|pages=1053–1065|doi=10.1111/ddg.13340|pmid=28976107|s2cid=27585177|url=http://eprints.hud.ac.uk/id/eprint/33816/1/AcceptedVersion.pdf}}</ref>

=== Non-syndromic ichthyosis ===
{| class="wikitable"
|+
!Name
![[Online Mendelian Inheritance in Man|OMIM]]
!Mode Of Inheritance
!Gene(s)
|-
|[[Ichthyosis vulgaris]]
|{{OMIM|146700||none}}
|Autosomal semi-dominant
|''[[FLG (gene)|FLG]]''
|-
|[[X-linked recessive ichthyosis]]
|{{OMIM|308100||none}}
|X-linked recessive 
|''[[STS (gene)|STS]]''
|-
|[[Harlequin-type ichthyosis|Harlequin ichthyosis]]
|{{OMIM|242500||none}}
|Autosomal recessive
|''[[ABCA12]]''
|-
|[[Congenital ichthyosiform erythroderma|Congenital ichthyosiform erythoderma]]
|{{OMIM|242100||none}}
|Autosomal recessive
|''[[TGM1|TGMI1]], [[NIPAL4]], [[ALOX12B]], [[ALOXE3]], [[ABCA12]], [[CYP4F22]], NIPAL4, LIPN, CERS3, PNPLA1, ST14, CASP14''
|-
|[[Lamellar ichthyosis]]
|{{OMIM|242300||none}}
|Autosomal recessive
|[[TGM1|''TGMI1'']]'', [[NIPAL4]], [[ALOX12B]], [[ALOXE3]], [[ABCA12]], [[CYP4F22]], NIPAL4, LIPN, CERS3, PNPLA1, ST14, CASP14''
|-
|Self improving congenital ichthyosis
|{{OMIM|242300||none}}
|Autosomal recessive
|''[[TGM1]], [[ALOX12B]], [[ALOXE3]]''
|-
|Bathing suit ichthyosis
|{{OMIM|242300||none}}
|Autosomal recessive
|''[[TGM1|TGMI1]]''
|-
|[[Epidermolytic hyperkeratosis|Epidermolytic ichthyosis]]
|{{OMIM|113800||none}}
|Autosomal dominant
|''[[Keratin 1|KRT1]], [[Keratin 10|KRT10]]''
|-
|[[Ichthyosis bullosa of Siemens|Superficial epidermolytic ichthyosis]]
|{{OMIM|146800||none}}
|Autosomal dominant
|''[[KRT2]]''
|-
|Annular epidermolytic ichthyosis
|{{OMIM|607602||none}}
|Autosomal dominant
|[[Keratin 1|''KRT1'']]'', [[Keratin 10|KRT10]]''
|-
|[[Ichthyosis hystrix|Ichthyosis Curth-Macklin]]
|{{OMIM|146590||none}}
|Autosomal dominant
|[[Keratin 1|''KRT1'']]
|-
|Autosomal recessive epidermolytic ichthyosis
|{{OMIM|113800||none}}
|Autosomal recessive
|[[Keratin 10|''KRT10'']]
|-
|[[Congenital reticular ichthyosiform erythroderma]]
|{{OMIM|609165||none}}
|Autosomal dominant
|[[Keratin 1|''KRT1'']]'', [[Keratin 10|KRT10]]''
|-
|Epidermolytic nevi
|{{OMIM|113800||none}}
|Postzygotic mosaicism
|[[Keratin 1|''KRT1'']]'', [[Keratin 10|KRT10]]''
|-
|Loricrin keratoderma
|{{OMIM|604117||none}}
|Autosomal dominant
|''LOR''
|-
|[[Erythrokeratodermia variabilis]]
|{{OMIM|133200||none}}
|Autosomal dominant
|''[[GJB3]], [[GJB4]]''
|-
|Peeling skin disease
|{{OMIM|270300||none}}
|Autosomal recessive
|''[[Corneodesmosin|CDSN]]''
|-
|[[Keratosis linearis with ichthyosis congenita and sclerosing keratoderma syndrome|Keratosis linearis with ichthyosis congenita and sclerosing keratoderma]]
|{{OMIM|601952||none}}
|Autosomal recessive
|''[[POMP]]''
|}

=== Syndromic ichthyosis===
{| class="wikitable"
|+
![[Name]]
![[Online Mendelian Inheritance in Man|OMIM]]
![[Mode Of Inheritance]]
![[Gene]] (s)
|-
|[[X-linked ichthyosis|X-linked recessive ichthyosis syndromic forms]]
|{{OMIM|308700||none}}{{OMIM|300500||none}}{{OMIM|300533||none}}
|[[X-linked recessive]]
|''[[Steroid sulfatase|STS]]''
|-
|[[Ichthyosis follicularis with alopecia and photophobia syndrome]]
|{{OMIM|308205||none}}
|[[X-linked recessive]]
|''[[MBTPS2]]''
|-
|[[Conradi–Hünermann syndrome|Conradi-Hunermann-Happle syndrome]]
|{{OMIM|302960||none}}
|[[X-linked dominant]]
|''EBP''
|-
|[[Netherton syndrome]]
|{{OMIM|256500||none}}
|[[Autosomal recessive]]
|''[[SPINK5]]''
|-
|[[Ichthyosis-hypotrichosis syndrome]]
|{{OMIM|610765||none}}
|[[Autosomal recessive]]
|''[[ST14]]''
|-
|[[Trichothiodystrophy]]
|{{OMIM|601675||none}}
|[[Autosomal recessive]]
|''[[ERCC2]], [[XPB|ERCC3]], [[GTF2H5]]''
|-
|[[Trichothiodystrophy|Trichothiodystrophy (non-congenital forms)]]
|{{OMIM|275550||none}}{{OMIM|211390||none}}{{OMIM|601675||none}}
|[[Autosomal recessive]]
|''[[MPLKIP|C7Orf11]], TTDN1''
|-
|[[Sjögren–Larsson syndrome|Sjögren-Larsson syndrome]]
|{{OMIM|270200||none}}
|[[Autosomal recessive]]
|''[[ALDH3A2]]''
|-
|[[Refsum disease|Refsum's disease]]
|{{OMIM|266500||none}}
|[[Autosomal recessive]]
|''[[PHYH]], [[PEX7]]''
|-
|[[Mental retardation, enteropathy, deafness, neuropathy, ichthyosis, keratoderma syndrome]]
|{{OMIM|609528||none}}
|[[Autosomal recessive]]
|''[[SNAP29]]''
|-
|[[Arthrogryposis, renal dysfunction, cholestasis syndrome]]
|{{OMIM|208085||none}}
|[[Autosomal recessive]]
|''[[VPS33B]]''
|-
|[[Keratitis–ichthyosis–deafness syndrome|Keratitis-ichthyosis-deafness syndrome]]
|{{OMIM|602450||none}}{{OMIM|148210||none}}
|[[Autosomal dominant]]
|''[[GJB2]]''
|-
|[[Neutral lipid storage disease|Neutral lipid storage disease with ichthyosis]]
|{{OMIM|275630||none}}
|[[Autosomal recessive]]
|''[[ABHD5]]''
|-
|[[Ichthyosis prematurity syndrome]]
|{{OMIM|608649||none}}
|[[Autosomal recessive]]
|''[[SLC27A4]]''
|-
|[[Neu–Laxova syndrome]]
|{{OMIM|256520||none}}{{OMIM|616038||none}}
|[[autosomal recessive]]
|''[[PHGDH]]'', ''[[PSAT1]]'' and ''[[PSPH]]''
|}

=== Non-genetic ichthyosis ===
*[[Ichthyosis acquisita]]

==Diagnosis==
A physician often can diagnose ichthyosis by looking at the skin. A family history is also useful in determining the mode of inheritance. In some cases, a skin biopsy is done to help to confirm the diagnosis while in others [[genetic testing]] may be helpful in making a diagnosis. Diabetes has not been definitively linked to acquired ichthyosis or ichthyosis vulgaris; however, there are case reports associating new onset ichthyosis with diabetes.<ref>{{cite journal | last1 = Scheinfeld | first1 = N | last2 = Libkind | first2 = M | last3 = Freilich | first3 = S | title = New-onset ichthyosis and diabetes in a 14-year-old. | journal = Pediatric Dermatology | volume = 18 | issue = 6 | pages = 501–3 | year = 2001 | pmid = 11841637 | doi = 10.1046/j.1525-1470.2001.1862004.x | s2cid = 22440127 }}</ref>

Ichthyosis has been found to be more common in Native American, Asian, Mongolian groups.{{citation needed|date=June 2020}} There is no way to prevent ichthyosis.

Ichthyosis is a genetically and phenotypically [[Heterogeneous condition|heterogeneous disease]] that can be isolated and restricted to the skin manifestations or associated with extracutaneous symptoms, one of which is limb reduction defect known as [[CHILD syndrome]], a rare inborn error of metabolism of cholesterol biosynthesis that is usually restricted to one side of the body. One case with symptoms matching CHILD syndrome has been described as having a likely-different cause.<ref>Shawky, R. M., Elsayed, S. M., & Amgad, H. (2016). Autosomal recessive ichthyosis with limb reduction defect: A simple association and not CHILD syndrome. Egyptian Journal of Medical Human Genetics, 17(3), 255-258.</ref>

==Treatments==
Treatments for ichthyosis often take the form of topical application of creams and [[emollient]] oils, in an attempt to hydrate the skin. Creams containing a high percentage of urea or lactic acid have been shown to work exceptionally well in some cases.<ref>{{Cite journal | title = The action of a urea—lactic acid ointment in ichthyosis | journal = British Journal of Dermatology | volume = 94 | issue = 2 | pages = 145–153 | author = Cicely Blair | date = February 1976 | doi = 10.1111/j.1365-2133.1976.tb04363.x | pmid = 943169 | s2cid = 29854858 }}</ref> Application of [[propylene glycol]] is another treatment method. [[Retinoid]]s are used for some conditions.

Exposure to sunlight may improve{{Citation needed|date = October 2015}} or worsen the condition. In some cases, excess dead skin sloughs off much better from wet tanned skin after bathing or a swim, although the dry skin might be preferable to the damaging effects of sun exposure.

There can be ocular manifestations of ichthyosis, such as [[cornea]]l and ocular surface diseases. Vascularizing [[keratitis]], which is more commonly found in congenital keratitis-ichythosis-deafness (KID), may worsen with [[isotretinoin]] therapy.

==Other animals==
Ichthyosis or ichthyosis-like disorders exist for several types of [[animal]]s, including [[cattle]], [[chicken]]s, [[llama]]s, [[Mus (genus)|mice]], and dogs.<ref>Sundberg, John P., [https://books.google.com/books?id=5XW0CvVHwSUC ''Handbook of Mouse Mutations with Skin and Hair Abnormalities''], Page 333, Published by CRC Press, 1994, {{ISBN|0-8493-8372-2}}</ref> Ichthyosis of varying severity is well documented in some popular [[dog breed|breeds]] of domestic [[dog]]s. The most common breeds to have ichthyosis are [[Golden Retriever]]s, [[American bulldog]]s, [[Jack Russell terrier]]s, and [[Cairn terrier]]s.<ref>{{cite web|url=https://www.theskinvet.co.nz/ichthyosis-golden-retrievers/|title=Ichthyosis in golden retrievers (Excessive scale or dandruff flakes)|publisher=The skin vet|website=[[The skin vet]]|archive-url=https://web.archive.org/web/20240715112457/https://www.theskinvet.co.nz/ichthyosis-golden-retrievers/|archive-date=15 July 2024}}</ref><ref>Gross, Thelma Lee, [https://books.google.com/books?id=VKa2Wo3Wc-kC ''Veterinary Dermatopathology''], Page 174-179, Published by Blackwell Publishing, 2004, {{ISBN|0-632-06452-8}}</ref>

== In fiction ==
* [[Arthur Conan Doyle]] – "[[The Adventure of the Blanched Soldier]]"
* [[Michel Faber]] – ''[[The Crimson Petal and the White]]''
* [[George R. R. Martin]] – ''[[A Song of Ice and Fire]]''
* [[Bernard Minier]] – ''Sisters''
* [[DC Comics]] - [[Killer Croc]]
* [[Osamu Tezuka]] - [[Black Jack (manga)|Black Jack]]

==See also==
* [[Skin disease]]
* [[Ichthyosis en confetti]]
* [[List of cutaneous conditions]]
* [[List of cutaneous neoplasms associated with systemic syndromes]]

==References==
{{Reflist}}

== External links ==
{{Medical resources
| DiseasesDB      = 6646
| ICD10           = {{ICD10|Q|80||q|80}}
| ICD9            = {{ICD9|757.1}}
| ICDO            = 
| OMIM            = 
| MedlinePlus     = 
| eMedicineSubj   = article
| eMedicineTopic  = 1198130
| MeshID          = D007057
| Orphanet        = 79354
}}
{{Commons category}}
* {{DermAtlas|1896838546}}
* [https://www.niams.nih.gov/health-topics/ichthyosis Ichthyosis Overview]&nbsp;- US National Institute of Arthritis and Musculoskeletal and Skin Diseases
* [https://ichthyosis.info European Network for Ichthyosis – International patients' network run by national European patients' associations]

{{Diseases of the skin and appendages by morphology}}
{{Congenital malformations and deformations of integument}}
{{Authority control}}

[[Category:Genodermatoses]]
[[Category:Rare diseases]]