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|Classification and external resources|
Ichthyosis is recognized by rough, scaly skin exhibited by patients.
Ichthyosis (plural Ichthyoses) is a heterogeneous family of at least 28, generalized, mostly genetic skin disorders. All types of ichthyosis have dry, thickened, scaly or flaky skin. In many types there is cracked skin, which is said to resemble the scales on a fish; the word ichthyosis comes from the Ancient Greek ιχθύς (ichthys), meaning "fish." The severity of symptoms can vary enormously, from the mildest types such as ichthyosis vulgaris which may be mistaken for normal dry skin up to life-threatening conditions such as harlequin type ichthyosis. The most common type of ichthyosis is ichthyosis vulgaris, accounting for more than 95% of cases.
There are many types of Ichthyosis and an exact diagnosis may be difficult. Types of Ichthyosis are classified by their appearance and their genetic cause. Ichthyosis caused by the same gene can vary considerably in severity and symptoms. Some Ichthyoses don't appear to fit exactly into any one type. Also different genes can produce Ichthyoses with similar symptoms. Of note, X-linked Ichthyosis is associated with Kallmann syndrome (close to KAL1 gene). The most common or well-known types are as follows:
Genetic simple ichthyoses 
|X-linked ichthyosis||308100||STS||Steroid sulfatase|
|Congenital ichthyosiform erythroderma, Nonbullous (nbCIE)||242100||TGM1, ALOXE3/ALOX12B||Transglutaminase 1
Arachidonate lipoxygenase 3
Arachidonate 12-lipoxygenase, 12R type
|Epidermolytic hyperkeratosis(bullous ichthyosis, bCIE)||113800||KRT1, KRT10||Keratins|
|Harlequin-type ichthyosis||242500||ABCA12||ATP-binding cassette transporter 12|
|Ichthyosis bullosa of Siemens||146800||KRT2||Keratin 2A|
|Ichthyosis hystrix, Curth-Macklin type||146590||KRT1||Keratin 1|
|Hystrix-like ichthyosis with deafness||602540||GJB2||Connexin-26 (Gap junction beta-2)|
|Lamellar ichthyosis, type 1||242300||TGM1||Transglutaminase 1|
|Lamellar ichthyosis, type 2||601277||ABCA12||ATP-binding cassette transporter 12|
|Lamellar ichthyosis, type 3||604777||CYP4F22||Cytochrome P450, subfamily 4F, polypeptide 22|
|Lamellar ichthyosis, type 4||613943||LIPN||Lipase family, member N|
|Lamellar ichthyosis, type 5||606545||Unknown|
Genetic disease with ichthyosis 
|CHILD Syndrome||308050||NSHDL||NAD(P) dependent steroid dehydrogenase-like|
|Conradi-Hünermann syndrome||302960||EBP||Emopamil binding protein|
|Ichthyosis follicularis with alopecia and photophobia syndrome||308205||MBTPS2||Membrane-bound transcription factor peptidase, site 2|
|Netherton syndrome||256500||SPINK5||Serine peptidase inhibitor, Kazal type 5|
|Neutral lipid storage disease with ichthyosis||275630||ABHD5||1-acylglycerol-3-phosphate O-acyltransferase|
|Adult Refsum disease||266500||PHYH
|Ichthyosis and male hypogonadism||308200||?|
|Sjögren-Larsson syndrome||270200||ALDH3A2||Fatty acid dehydrogenase|
|Photosensitive trichothiodystrophy (IBIDS syndrome)||601675||ERCC2, ERCC3, GTF2H5||Transcription factor IIH components|
|Gaucher Disease, type 2||GBA||Glucocerebrosidase|
Non-genetic ichthyosis 
A physician often can diagnose ichthyosis by looking at the skin. A family history is very useful. In some cases, a skin biopsy is done to help to confirm the diagnosis. In a biopsy, a small piece of skin is removed and examined under a microscope. In some instances, 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 is not more or less common in any ethnic group. As of now, there is no way to prevent ichthyosis.
Treatments for ichthyosis often take the form of topical application of creams and emollient oils, in an attempt to hydrate the skin. Creams containing lactic acid have been shown to work exceptionally well in some cases. Applicaton of Propylene Glycol has been used as another treatment method. Retinoids are also 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.
Ichthyosis in animals 
Ichthyosis or ichthyosis-like diseases 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.
See also 
- Skin disease
- Ichthyosis en confetti
- List of cutaneous conditions
- List of cutaneous neoplasms associated with systemic syndromes
- FAQ, Foundation for Ichthyosis & Related Skin Types (F.I.R.S.T)
- thefreedictionary.com/ichthyosis citing: Gale Encyclopedia of Medicine. Copyright 2008
- Ichthyosis, John Hopkins Health Information Library
- 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.
- Types of Ichthyosis, Foundation for Ichthyosis & Related Skin Types (F.I.R.S.T)
- 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.
- Sundberg, John P., Handbook of Mouse Mutations with Skin and Hair Abnormalities, Page 333, Published by CRC Press, 1994, ISBN 0-8493-8372-2
- Gross, Thelma Lee, Veterinary Dermatopathology, Page 174-179, Published by Blackwell Publishing, 2004, ISBN 0-632-06452-8
- Foundation for Ichthyosis and Related Skin Types USA
- British Ichthyosis Support Group
- Non-Profit foundation 'Global Ichthyosis Syndrome Network'
- European Network for Ichthyosis
- DermAtlas 1896838546
- Foundation for Ichthyosis Research in MONACO