Ichthyosis Explained

Ichthyosis
Synonyms:Ichthyoses
Field:Dermatology

Ichthyosis (also named fish scale disease)[1] is a family of genetic skin disorders characterized by dry, thickened, scaly skin.[2] The more than 20 types of ichthyosis range in severity of symptoms, outward appearance, underlying genetic cause and mode of inheritance (e.g., dominant, recessive, autosomal or X-linked).[3] Ichthyosis comes from the Greek, literally 'fish', since dry, scaly skin is the defining feature of all forms of ichthyosis.[4]

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.[5]

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. 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). The most common or well-known types are:[6]

Non-syndromic ichthyosis

!Name!OMIM!Mode Of Inheritance!Gene(s)
Ichthyosis vulgarisAutosomal semi-dominantFLG
X-linked recessive ichthyosisX-linked recessive STS
Harlequin ichthyosisAutosomal recessiveABCA12
Congenital ichthyosiform erythodermaAutosomal recessiveTGMI1, NIPAL4, ALOX12B, ALOXE3, ABCA12, CYP4F22, NIPAL4, LIPN, CERS3, PNPLA1, ST14, CASP14
Lamellar ichthyosisAutosomal recessiveTGMI1, NIPAL4, ALOX12B, ALOXE3, ABCA12, CYP4F22, NIPAL4, LIPN, CERS3, PNPLA1, ST14, CASP14
Self improving congenital ichthyosisAutosomal recessiveTGM1, ALOX12B, ALOXE3
Bathing suit ichthyosisAutosomal recessiveTGMI1
Epidermolytic ichthyosisAutosomal dominantKRT1, KRT10
Superficial epidermolytic ichthyosisAutosomal dominantKRT2
Annular epidermolytic ichthyosisAutosomal dominantKRT1, KRT10
Ichthyosis Curth-MacklinAutosomal dominantKRT1
Autosomal recessive epidermolytic ichthyosisAutosomal recessiveKRT10
Congenital reticular ichthyosiform erythrodermaAutosomal dominantKRT1, KRT10
Epidermolytic neviPostzygotic mosaicismKRT1, KRT10
Loricrin keratodermaAutosomal dominantLOR
Erythrokeratodermia variabilisAutosomal dominantGJB3, GJB4
Peeling skin diseaseAutosomal recessiveCDSN
Keratosis linearis with ichthyosis congenita and sclerosing keratodermaAutosomal recessivePOMP

Syndromic ichthyosis

!Name!OMIM!Mode Of Inheritance!Gene (s)
X-linked recessive ichthyosis syndromic formsX-linked recessiveSTS
Ichthyosis follicularis with alopecia and photophobia syndromeX-linked recessiveMBTPS2
Conradi-Hunermann-Happle syndromeX-linked dominantEBP
Netherton syndromeAutosomal recessiveSPINK5
Ichthyosis-hypotrichosis syndromeAutosomal recessiveST14
TrichothiodystrophyAutosomal recessiveERCC2, ERCC3, GTF2H5
Trichothiodystrophy (non-congenital forms)Autosomal recessiveC7Orf11, TTDN1
Sjögren-Larsson syndromeAutosomal recessiveALDH3A2
Refsum's diseaseAutosomal recessivePHYH, PEX7
Mental retardation, enteropathy, deafness, neuropathy, ichthyosis, keratoderma syndromeAutosomal recessiveSNAP29
Arthrogryposis, renal dysfunction, cholestasis syndromeAutosomal recessiveVPS33B
Keratitis-ichthyosis-deafness syndromeAutosomal dominantGJB2
Neutral lipid storage disease with ichthyosisAutosomal recessiveABHD5
Ichthyosis prematurity syndromeAutosomal recessiveSLC27A4
Neu–Laxova syndromeautosomal recessivePHGDH, PSAT1 and PSPH

Non-genetic ichthyosis

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.[7]

Ichthyosis has been found to be more common in Native American, Asian, Mongolian groups. There is no way to prevent ichthyosis.

Ichthyosis is a genetically and phenotypically 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.[8]

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.[9] Application of propylene glycol is another treatment method. Retinoids are used for some conditions.

Exposure to sunlight may improve 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 corneal 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 animals, including cattle, chickens, llamas, mice, and dogs.[10] Ichthyosis of varying severity is well documented in some popular breeds of domestic dogs. The most common breeds to have ichthyosis are Golden Retrievers, American bulldogs, Jack Russell terriers, and Cairn terriers.[11]

See also

External links

Notes and References

  1. Dorf . Inger LH . Schmidt . Sigrún AJ . Sommerlund . Mette . Koppelhus . Uffe . November 2021 . Validity of First-Time Diagnoses of Darier's Disease in the Danish National Patient Registry . Clinical Epidemiology . 13 . 1063–1069 . 10.2147/clep.s326518 . 1179-1349. free . 34795531 . 8594618 .
  2. Book: James . William D. . Elston . Dirk . Treat . James R. . Rosenbach . Misha A. . Neuhaus . Isaac . Andrews' Diseases of the Skin: Clinical Dermatology . 2020 . Elsevier . Edinburgh . 978-0-323-54753-6 . 563–565 . 13th . https://books.google.com/books?id=UEaEDwAAQBAJ&pg=PA563 . en . 27. Genodermatoses and congenital anomalies .
  3. http://medical-dictionary.thefreedictionary.com/ichthyosis thefreedictionary.com/ichthyosis
  4. Web site: Ichthyosis. Johns Hopkins Medicine. Health Information Library. https://web.archive.org/web/20090202114600/http://www.hopkinsmedicine.org/health_information_library/index.html?ArticleID=19366. 2 February 2009.
  5. Okulicz JF, Schwartz RA . 2003 . Hereditary and acquired ichthyosis vulgaris . International Journal of Dermatology . 42 . 2 . 95–8 . 12708996 . 10.1046/j.1365-4362.2003.01308.x . 20029085 .
  6. Oji. Vinzenz. Preil. Marie-Luise. Kleinow. Barbara. Wehr. Geske. Fischer. Judith. Hennies. Hans Christian. Hausser. Ingrid. Breitkreutz. Dirk. Aufenvenne. Karin. Stieler. Karola. Tantcheva-Poór. Illiana. 2017. S1 guidelines for the diagnosis and treatment of ichthyoses - update. JDDG: Journal der Deutschen Dermatologischen Gesellschaft. en. 15. 10. 1053–1065. 10.1111/ddg.13340. 28976107. 27585177.
  7. Scheinfeld . N . Libkind . M . Freilich . S . New-onset ichthyosis and diabetes in a 14-year-old. . Pediatric Dermatology . 18 . 6 . 501–3 . 2001 . 11841637 . 10.1046/j.1525-1470.2001.1862004.x . 22440127 .
  8. 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.
  9. The action of a urea—lactic acid ointment in ichthyosis . British Journal of Dermatology . 94 . 2 . 145–153 . Cicely Blair . February 1976 . 10.1111/j.1365-2133.1976.tb04363.x . 943169 . 29854858 .
  10. Sundberg, John P., Handbook of Mouse Mutations with Skin and Hair Abnormalities, Page 333, Published by CRC Press, 1994,
  11. Gross, Thelma Lee, Veterinary Dermatopathology, Page 174-179, Published by Blackwell Publishing, 2004,