Ichthyosis

Classification according to ICD-10
Q80.-	Ichthyosis congenita
Q80.0	Ichthyosis vulgaris
Q80.1	X-linked recessive ichthyosis
Q80.2	Lamellar ichthyosis
Q80.3	Bullous congenital ichthyosiform erythroderma
Q80.4	Ichthyosis congenita gravis (Harlequin Infetus)
Q80.8	Other congenital ichthyosis
Q80.9	Ichthyosis congenita, unspecified
L85.0	Acquired ichthyosis
Q82.-	Other congenital malformations of the skin
Q82.8	Congenital malformation of the skin, unspecified
ICD-10 online (WHO version 2019)

severe ichthyosis, 1888

Ichthyosis ( ancient Greek ἰχθύς , ichthýs , fish; synonymous with the internationally used term ichthyosis) is a collective term for cornification disorders of the skin , which are mostly caused by genetic defects . Ichthyoses are not contagious, can be very different and can be improved with intensive care, but are not curable. Sometimes the appearance improves in the course of life.

The most common hereditary disease of the skin and one of the most common hereditary diseases of all is ichthyosis vulgaris . It is one of the lighter ichthyoses and is noticeable through dry, rough skin, flakes and occasional itching . Roughly estimated, it occurs on average once in 300 people.

history

The ichthyosis was first medically documented by Edward Lambert, who was presented to the Royal Society in London on March 16, 1731 . Lambert was the child of healthy parents and had a severe form of ichthyosis hystrix . He married and inherited ichthyosis to six of his offspring. He died in an accident in 1806 at the age of ninety.

Pathogenesis

The skin is constantly renewing itself. The upper skin ( epidermis ) consists of several layers. New cells are formed in the lowest basal layer and migrate to the layers above. On the way up keratinize the cells and die.

Finally they get into the horny layer. This consists of thin layers of flat dead cells. The cells of the horny layer contain keratin , a tough, thread-like protein that gives the horny layer its strength. Fats are stored between the cells, which ensure that the skin is water-repellent. The horny layer regulates the body's moisture balance. Microscopic flakes are constantly peeling off the horny layer.

Due to cell migration, the horny layer renews itself approximately every four weeks. With healthy skin, new cell formation and exfoliation are in balance. In ichthyoses, the natural peeling is disturbed and larger visible flakes of skin form . In some forms of ichthyosis, the formation of scales is also increased (proliferation hyperkeratosis ).

Symptoms

The characteristic feature of ichthyoses is a thickening of the top layer of skin, the horny layer and visible skin flakes . In some forms, the skin is very reddened.

Blistering ichthyoses (congenital ichthyosiform erythroderma Brocq) are rare, as are combined ichthyoses with additional health disorders ( Netherton syndrome , harlequin ichthyosis ). Acquired (i.e. not congenital ) forms of ichthyosis, which are an expression of other underlying diseases , also occur rarely .

In the case of mild ichthyoses (only recognizable for a certain time after birth, ichthyosis vulgaris group) the symptoms are less severe; however, the skin is very dry, especially in winter, possibly flaky, and occasionally itching may occur. In severe forms (already recognizable on the day of birth, ichthyosis congenita group), more scales are formed.

The normal skin functions are disturbed by the ichthyosis, so the skin can often not sweat or the skin breathing is impaired. The body can overheat faster with physical exertion, so it is important to always have plenty of water with you in summer and when exercising. Swimming is often a very suitable sport because the water is cooling from the outside.

The skin of people with blistering ichthyosis is very sensitive. For example, if the sole of the foot is affected, painful water blisters can form on the sole of the foot after just a short distance. This is very cumbersome when a baby learns to walk. Therapeutic riding can help the child to train balance , muscles and sense of rhythm without putting any strain on the feet.

A characteristic clinical picture in newborns that can occur in some ichthyoses is called a collodion baby. The skin looks as if it were covered with a layer of collodion .

therapy

Daily skin care is very complex. The skin often needs to be cream and bathed. In addition, the cornea must be removed with keratolytic agents . Otherwise there is a risk of painful cracks in the dry, brittle "double skin". For many ichthyoses, ointments , skin creams or lotions with urea as an active ingredient have so far been the most suitable treatment.

Bathing in the Dead Sea often has a positive effect on the condition of the skin.

In severe forms of ichthyosis, there is the option of systemic retinoid therapy, which, however, can also cause severe and sometimes irreversible side effects. Such a therapy has both keratolytic and inhibitory effects on the keratinization, but does not treat the genetically caused keratinization disorder.

For ichthyoses, there are so far only symptomatic therapies that aim to support desquamation or to heal side effects such as infections . No causal treatments are known for severe ichthyoses either . Initial research approaches, however, suggest, at least theoretically, that individual ichthyoses could be positively influenced by gene therapy methods (e.g. BD Roop, J. Chen, M. Arin, M. Braun-Falco).

Forms of ichthyosis in humans

The classification and nomenclature of ichthyoses is currently being revised.

Ichthyoses can be roughly divided into four groups, depending on when they first appeared and whether there are any additional features:

1. vulgar ichthyosis without further characteristics (English isolated vulgar ichthyosis )
2. Vulgar ichthyoses with other characteristics (complex ichthyoses, English associated vulgar ichthyosis )
3. congenital (congenital) ichthyosis without further characteristics (English isolated congenital ichthyosis )
4. congenital ichthyoses with further characteristics (complex ichthyoses, English associated congenital ichthyosis )

In this context, “congenital” means that newborns already show signs of ichthyosis on the day of birth.
“Vulgar” means that the ichthyosis usually only becomes noticeable later.

Autosomal means that the genetic defect is on a normal chromosome and not on a sex chromosome . Autosomal inheritance is therefore not gender-linked. In addition to an autosomal dominant form ( incidence 1: 300), there is an x-linked recessive form in which male offspring become ill (incidence 1: 4000).

In the following list, besides the name, it is also indicated how the ichthyosis is inherited, and in some cases the estimated frequency is also given.

Surname	Altered proteins (known)	Mutation in the gene (known)	Inheritance	estimated frequency
Vulgar ichthyoses with no other characteristics
Autosomal Dominant Ichthyosis Vulgaris (ADI)	Filaggrin	FLG	autosomal semidominant	1: 300
Autosomal recessive congenital ichthyosis (ARCI)			autosomal recessive	1: 1,000,000
X-linked recessive ichthyosis vulgaris (XRI)	Steroid sulfatase	STS	X-linked recessive	1: 4,000
Vulgar ichthyoses with additional features
Refsum syndrome	Phytanoyl-CoA hydroxylase , peroxin-7	PHYH , PEX7	autosomal recessive
Congenital ichthyoses with no other characteristics
Lamellar ichthyoses	Transglutaminase -1	TGM1 , ichthyin , CYP4F22 , ABCA12	autosomal recessive	approx. 1: 300,000
Congenital ichthyosiform erythroderma (CIE)	Transglutaminase-1, 12R-lipoxygenase , lipoxygenase -3	TGM1 , ALOX12B , ALOXE3 , ABHD5 , Ichthyin	autosomal recessive	approx. 1: 300,000
Bullous congenital ichthyosiform erythroderma Brocq (epidermolytic hyperkeratosis, EHK)	Keratins	KRT1 , KRT10	autosomal dominant	approx. 1: 500,000
Bullous ichthyosis Siemens	Keratin-2e	KRT2E	autosomal dominant
Ichthyosis hystrix Curth-Macklin	Cytokeratin-1	KRT1	autosomal dominant
Harlequin ichthyosis (Ichthyosis gravis)		ABCA12	autosomal recessive	1: 3,000,000 (estimate)
Congenital ichthyoses with additional features
KID syndrome (English keratitis, ichthyosis, deafness ) erythrokeratoderma of Burns	Connexin-26	GJB2	autosomal dominant
Netherton Syndrome	Serine protease inhibitor LEKTI	SPINK5	autosomal recessive
Sjogren Larsson Syndrome	Fatty acid aldehyde dehydrogenase	ALD3H2	autosomal recessive
Tay syndrome	TFIIH helicase XPB	ERCC3	autosomal recessive

Ichthyoses in veterinary medicine

In veterinary medicine , ichthyoses are diagnosed particularly in dogs and cattle , and rarely in other domestic animals. The disease was described in cattle as early as 1850. It is a congenital form ( ichthyosis congenita ) that is usually lethal - affected animals are usually stillborn. The inheritance in cattle is simply autosomal recessive, with the affected gene on chromosome 32.

Dogs with milder forms of ichthyosis can be treated symptomatically. A cure is not possible. Carriers of traits should not be used for breeding.

literature

• H. Traupe: The Ichthyoses - A Guide to Clinical Diagnosis, Genetic Counseling and Therapy . Springer Verlag, Heidelberg 1989, ISBN 3-540-19222-0 .
• U. Süsse-Krause, S. Wiegandt: People with Ichthyosis, an illustrated book . published by the self-help ichthyosis. 2003, ISBN 3-00-011199-9 .
• A. Herzog: Pareys Lexicon of Syndromes - Hereditary and breeding diseases of domestic and farm animals. Parey Buchverlag, Berlin 2001, ISBN 3-8263-3237-7 .

Web links

• NIRK network ichthyosis
• Diagnosis and therapy of ichthyoses . Guidelines of the German Dermatological Society
• Ichthyosis in a calf fetus : vet.cornell.edu , vet.cornell.edu

Individual evidence

1. ↑ dermis.net collodion baby at the Dermatology Information System, as of July 5, 2013.

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !