Ichthyosis

Ichthyosis
Ichthyosis is characterized by rough, scaly skin.
Classification and external resources
Specialty	Dermatology
ICD-10	Q80
ICD-9-CM	757.1
DiseasesDB	6646
Patient UK	Ichthyosis
MeSH	D007057

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 ἰχθύς (ichthys), meaning "fish."

The severity of symptoms can vary enormously, from the mildest, most common, type such as ichthyosis vulgaris which may be mistaken for normal dry skin up to life-threatening conditions such as harlequin type ichthyosis. Ichtyosis vulgaris accounts for more than 95% of cases.

Types

There are many types of ichthyoses and an exact diagnosis may be difficult. Types of ichthyoses are classified by their appearance and their genetic cause. Ichthyosis caused by the same gene can vary considerably in severity and symptoms. Some ichthyoses do not 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

Name	OMIM	Gene	Protein
Ichthyosis vulgaris	146700	FLG	Filaggrin
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	ALOXE3	Arachidonate lipoxygenase 3
Autosomal Recessive Congenital Ichthyosis	615023	CERS3	ceramide synthase 3

Genetic disease with ichthyosis

Name	OMIM	Gene	Protein
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
Keratitis-ichthyosis-deafness syndrome	148210	GJB2	Connexin-26
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 PEX7	Phytanoyl-CoA hydroxylase Peroxin 7
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	230900	GBA	Glucocerebrosidase

Non-genetic ichthyosis

• Ichthyosis acquisita

Diagnosis

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 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 has been found to be more common in any Native American, Asian, Mongolian group. As of now, there is no way to prevent ichthyosis.

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 lactic acid have been shown to work exceptionally well in some cases. Application 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.

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.

See also

• Skin disease
• Ichthyosis en confetti
• List of cutaneous conditions
• List of cutaneous neoplasms associated with systemic syndromes

External links

• 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
• Ichthyosis Overview - US National Institute of Arthritis and Musculoskeletal and Skin Diseases