Ichthyosis

Ichthyosis
Other namesIchthyoses
Ichthyosis is characterized by generalised scaly skin.
SpecialtyDermatology

Ichthyosis is a family of genetic skin disorders characterized by dry, thickened, scaly skin. 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). Ichthyosis comes from Greek ἰχθύς (ichthys) 'fish', since dry, scaly skin is the defining feature of all forms of ichthyosis.

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.

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). In order to replace outdated or potentially stigmatizing old disease names, there is an ongoing effort to redefine the classification of epidermal differentiation disorders (EDDs), including ichthyoses, based on the affected gene. This system also distinguishes between syndromic (sEDDs) and non-syndromic forms (nEDDs).

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:

Non-syndromic ichthyosis

New name(s) Previous name(s) OMIM Mode Of Inheritance Gene(s)
FLG-nEDD Ichthyosis vulgaris 146700 Autosomal semi-dominant FLG
ABCA12-nEDD Harlequin ichthyosis 242500 Autosomal recessive ABCA12
TGMI1-nEDD, NIPAL4-nEDD, ALOX12B-nEDD, ALOXE3-nEDD, ABCA12-nEDD,

LIPN-nEDD, CERS3-nEDD, PNPLA1-nEDD, CASP14-nEDD, ST14-sEDD

 Lamellar ichthyosis, Congenital ichthyosiform erythoderma
242100,
242300		 Autosomal recessive TGMI1, NIPAL4, ALOX12B, ALOXE3, ABCA12, CYP4F22, LIPN, CERS3, PNPLA1, ST14, CASP14
TGMI1-nEDD Bathing suit ichthyosis 242300 Autosomal recessive TGMI1
KRT1-nEDD epidermolytic,

KRT10-nEDD epidermolytic

 Epidermolytic ichthyosis 113800 Autosomal dominant, Autosomal recessive KRT1, KRT10
KRT2-nEDD Superficial epidermolytic ichthyosis 146800 Autosomal dominant KRT2
KRT1-nEDD-annular,

KRT10-nEDD-annular

 Annular epidermolytic ichthyosis 607602 Autosomal dominant KRT1, KRT10
KRT1-nEDD-spiny Ichthyosis Curth-Macklin 146590 Autosomal dominant KRT1
KRT1-nEDD revertant mosaic, KRT10-nEDD revertant mosaic Congenital reticular ichthyosiform erythroderma 609165 Autosomal dominant KRT1, KRT10
KRT1-nEDD mosaic, KRT2-nEDD mosaic, KRT10-nEDD mosaic, KRT16-nEDD mosaic, Epidermolytic nevi 113800 Postzygotic mosaicism KRT1, KRT2, KRT10, KRT16
LOR-pEDD Loricrin keratoderma 604117 Autosomal dominant LOR
GJB3-nEDD,

GJB4-nEDD

 Erythrokeratodermia variabilis 133200 Autosomal dominant GJB3, GJB4
CDSN-nEDD Peeling skin disease 270300 Autosomal recessive CDSN
POMP-nEDD Keratosis linearis with ichthyosis congenita and sclerosing keratoderma 601952 Autosomal recessive POMP
SLC27A4-nEDD Ichthyosis prematurity syndrome 608649 Autosomal recessive SLC27A4

Syndromic ichthyosis

New name(s) Previous Name(s) OMIM Mode Of Inheritance Gene (s)
STS-sEDD X-linked recessive ichthyosis syndromic forms 308700 300500 300533 X-linked recessive STS
MBTPS2-sEDD-IFAP,

MBTPS2-sEDD-ciatricial alopecia

 Ichthyosis follicularis with alopecia and photophobia syndrome 308205 X-linked recessive MBTPS2
EBP-sEDD Conradi-Hunermann-Happle syndrome 302960 X-linked dominant EBP
SPINK5-sEDD Netherton syndrome 256500 Autosomal recessive SPINK5
ST14-sEDD Ichthyosis-hypotrichosis syndrome 610765 Autosomal recessive ST14
ERCC2/XBP-sEDD-TTD,

ERCC3/XPB-sEDD-TTD, GTF2H5-sEDD-TTD

 Trichothiodystrophy 601675 Autosomal recessive ERCC2, ERCC3, GTF2H5
MPLKIP-sEDD Trichothiodystrophy (non-congenital forms) 275550 211390 601675 Autosomal recessive C7Orf11, TTDN1
ALDH3A2-sEDD Sjögren-Larsson syndrome 270200 Autosomal recessive ALDH3A2
PHYH-sEDD, PEX7-sEDD Refsum's disease 266500 Autosomal recessive PHYH, PEX7
SNAP29-sEDD Mental retardation, enteropathy, deafness, neuropathy, ichthyosis, keratoderma syndrome 609528 Autosomal recessive SNAP29
VPS33B-sEDD Arthrogryposis, renal dysfunction, cholestasis syndrome 208085 Autosomal recessive VPS33B
GJB2-sEDD-KID Keratitis-ichthyosis-deafness syndrome 602450 148210 Autosomal dominant GJB2
ABHD5-sEDD Neutral lipid storage disease with ichthyosis 275630 Autosomal recessive ABHD5
PHGDH-sEDD, PSAT1-sEDD, PSPH-sEDD Neu–Laxova syndrome 256520 616038 autosomal recessive PHGDH, PSAT1, 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.

Ichthyosis has been found to be more common in Native American, Asian, Mongolian groups.[citation needed] 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.

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

Exposure to sunlight may improve[citation needed] 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. 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.

In fiction

See also

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. doi:10.2147/clep.s326518. ISSN 1179-1349. PMC 8594618. PMID 34795531.
  2. ↑ James, William D.; Elston, Dirk; Treat, James R.; Rosenbach, Misha A.; Neuhaus, Isaac (2020). "27. Genodermatoses and congenital anomalies". Andrews' Diseases of the Skin: Clinical Dermatology (13th ed.). Edinburgh: Elsevier. pp. 563–565. ISBN 978-0-323-54753-6.
  3. ↑ Dabrowski, Mark. "Ichthyosis". Health Information Library. Johns Hopkins Medicine. Archived from the original on 2 February 2009.
  4. ↑ Okulicz JF, Schwartz RA (2003). "Hereditary and acquired ichthyosis vulgaris". International Journal of Dermatology. 42 (2): 95–8. doi:10.1046/j.1365-4362.2003.01308.x. PMID 12708996. S2CID 20029085.
  5. 1 2 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" (PDF). JDDG: Journal der Deutschen Dermatologischen Gesellschaft. 15 (10): 1053–1065. doi:10.1111/ddg.13340. PMID 28976107. S2CID 27585177. Archived (PDF) from the original on 2019-04-30. Retrieved 2020-08-30.
  6. ↑ Paller, Amy S; Teng, Joyce; Mazereeuw-Hautier, Juliette; Hernández-Martín, Ángela; Granier Tournier, Céline; Hovnanian, Alain; Aldwin-Easton, Mandy; Tadini, Gianluca; Schwartz, Janice; Sprecher, Eli; Malovitski, Kiril; Ishida-Yamamoto, Akemi; Choate, Keith; Akiyama, Masashi; O’Toole, Edel A (2025-09-18). "Syndromic epidermal differentiation disorders: a new classification toward pathogenesis-based therapy". British Journal of Dermatology. 193 (4): 592–618. doi:10.1093/bjd/ljaf123. ISSN 0007-0963.
  7. ↑ Akiyama, Masashi; Choate, Keith; Hernández-Martín, Ángela; Aldwin-Easton, Mandy; Bodemer, Christine; Gostyński, Antoni; Hovnanian, Alain; Ishida-Yamamoto, Akemi; Malovitski, Kiril; O’Toole, Edel A; Paller, Amy S; Schmuth, Matthias; Schwartz, Janice; Sprecher, Eli; Teng, Joyce M C (2025-09-18). "Nonsyndromic epidermal differentiation disorders: a new classification toward pathogenesis-based therapy". British Journal of Dermatology. 193 (4): 619–641. doi:10.1093/bjd/ljaf154. ISSN 0007-0963.
  8. ↑ Scheinfeld, N; Libkind, M; Freilich, S (2001). "New-onset ichthyosis and diabetes in a 14-year-old". Pediatric Dermatology. 18 (6): 501–3. doi:10.1046/j.1525-1470.2001.1862004.x. PMID 11841637. S2CID 22440127.
  9. ↑ 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.
  10. ↑ Cicely Blair (February 1976). "The action of a urea—lactic acid ointment in ichthyosis". British Journal of Dermatology. 94 (2): 145–153. doi:10.1111/j.1365-2133.1976.tb04363.x. PMID 943169. S2CID 29854858.
  11. ↑ Sundberg, John P., Handbook of Mouse Mutations with Skin and Hair Abnormalities, Page 333, Published by CRC Press, 1994, ISBN 0-8493-8372-2
  12. ↑ "Ichthyosis in golden retrievers (Excessive scale or dandruff flakes)". The skin vet. The skin vet. Archived from the original on 15 July 2024.
  13. ↑ Gross, Thelma Lee, Veterinary Dermatopathology, Page 174-179, Published by Blackwell Publishing, 2004, ISBN 0-632-06452-8