GENODERMATOSES (Greek genos a sort, an origin + a dermatosis) — hereditary diseases of skin.
Statistical data on a hereditary dermatosis are still incomplete in connection with rather recent beginning of systematic genetic researches in dermatology. According to WHO data, about a third of all hereditary diseases make a dermatosis which hereditary genesis is proved. There are no standard criteria for G.'s description to a crust, time, the skin given about quantity of nosological forms of hereditary diseases are diverse. So, according to P. Popkhristov (1971), by 1956 from 197 known hereditary anomalies of development of a human body in 51 damage of skin was found. V. P. Efroimson (1968) specifies what in literature is described St. 100 hereditary anomalies of development of skin; according to Vogel and Dern (F. Vogel, H. Dern, 1969), also more than 100 genodermatoses and their versions are. Allocation of new forms G. continues. Such G. as an inborn pachyonychia with epidermal cysts, a family inborn kollagenoma, Gorlin's syndrome — Golttsa (alveolar cysts, anomalies of a backbone and edges in combination with a multiple bazalnokletochny nevus), Gardner's syndrome, Hartnup's disease, etc. are described.
According to a number of authors, hereditary factors in a varying degree influence emergence and character of a clinical current of all dermatosis. So, Hands and Wells (A. Rook, R. S. Wells, 1968) all dermatosis subdivides into three groups: 1) genetically caused diseases of skin and its appendages (according to incomplete data the group includes 34 dermatosis); 2) a dermatosis in which emergence the important role belongs to genetic predisposition (this group included, in particular, psoriasis, neurodermatitis, seborrhea); 3) a dermatosis with a variable clinical picture and the course of process depending on a genotype.
Hereditary pathology can be caused by various level of defeat of the genetic device. Cytogenetic researches found a number of the chromosomal diseases of the person caused by disturbances of both number, and structure of chromosomes (see. Chromosomal diseases ); napr, Klaynfelter's syndrome, Shereshevsky's syndrome — Turner, a Down syndrome, etc., a complex patol which changes includes also skin symptomatology. At Klaynfelter's syndrome multiple angiomas, a Crocq's disease, hron, the hypostatic dermatitis of the lower extremities which is followed quite often by ulcerations, an atrophy and a hyperpegmentation of skin are observed. According to L. A. Shteynlukht (1966), at a Down syndrome the skin symptomatology is observed at 80% of patients, being shown in the form of ikhtioziformny changes of skin, changes of nail plates and hair, dysfunctions grease and sweat glands.
Studying of a karyotype of skin diseases of hereditary genesis or dermatosis at which genetic predisposition is important did not find changes of quantity and structure of chromosomes, napr, at a disease of Recklinghausen, a violent epidermolysis, an ichthyosis, a pigmental xeroderma, keratodermias, a scleroderma, a pemphigus, a lupus erythematosus, psoriasis, an incontience of a pigment, etc. Obviously, at G. mutations are concentrated in smaller base unit of the hereditary device — in a gene or group of genes. Patterns at which there are mutations are unknown. A certain part is assigned to a consanguineous relation of parents. In 1906 E. Adrian pointed to a role of a consanguineous relation of parents in emergence at children of a violent epidermolysis, a pigmental xeroderma, etc.
Frequency of harmful mutations of the genes causing skin anomalies for many G. is known. In an experiment by means of artificial mutations at animals albinism, an atrichia, an ichthyosis, a keratosis, etc. are got. Genetic anomalies can be shown in any structural elements of skin. Thickness of skin, pilosis, secretion of glands, a xanthopathy are defined by features of a genotype of the person. The variety of mutations causes a wide range of various anomalies causing various patol, processes in skin — a dysplasia, dystrophy, disturbances of pigmentation, defeat of appendages of skin (hair, nails, grease and sweat glands).
Kokkeyn (E. A. Cockayne, 1962) allocated the following groups hereditary patol, processes and anomalies of skin and its appendages: fiziol, anomalies (heterochromia and premature canities of hair, freckles, lentigo, etc.), metabolic defects (albinism, pigmental xeroderma, porphyria, xanthomatosis, etc.), disturbances of development of elastic fabric (violent epidermolysis, hyper elastic skin, etc.), dyskeratoses (ichthyosis, keratodermia, Deverzhi's disease, etc.), ectodermal dysplasia (inborn alopecia, anonychia, hypertrichosis, etc.), anomalies of appendages of skin etc.
It is established that genes cause development and activity of enzymes. It is known St. 1500 hereditary enzymopathies of the person which part is followed by skin symptomatology. So, e.g., the argininosuktsinatatsiduriya (lack of enzyme of argininosuktsinat-lyase), a tsitrulemiya (lack of synthesis of an argininosuktsinat), a homocystinuria (lack of a fenilalaningidroksilaza), a tirozinemiya (lack of steam-oksifenilpiruvatgidroksilazy) are followed by changes of hair [Porter, Lobitts (P. S. Porter, W. Page of Lobitz), 1970]; at fenilketo nuriya the hypochromia of skin is observed, at diabetes — a hyperchromia of skin, at porphyrias — violent rashes and dyschromias; at a dislipoidoza the xanthomatosis is observed, at an agammaglobulinemia — a pyoderma, at a disproteinemia and an akatalaziya — necroses of skin, etc. Assume that albinism is caused by decrease of the activity or lack of enzyme of a tyrosinase, an enteropatichesky acrodermatitis — disturbance of exchange of amino acid of tryptophane.
Reliable data about enzymatic disturbances at all G. it is not obtained yet therefore the type of transfer of a mutant gene in generations and feature of its arrangement is the basis for modern genetic classification of genodermatoses (in autosomes or gonosomes). Consider also penetrance, expressivity of genes (see. Gene ), a possibility of polygenic inheritance, etc. (see. Inheritance ).
According to classification of G. offered by Blum (D. Bloom, 1965), taking into account the additions made by Ruk (1968) autosomal it is prepotent are inherited: adenoma of sebaceous glands, verrutsiformny akrokeratoz Hopf, partial albinism, Mibelli's angiokeratoma, an inborn aplasia of skin, atopic dermatitis, an ectodermal dysplasia, Elers's syndrome — Danlosa, a simple violent epidermolysis, a high-quality family pemphigus of Guzhero — Hailey — Hailey, a disease of Randyu — Oslera, an incontience of a pigment (Neghelli type), a disease to Darya, a keratoma of palms and soles, keloids, a neurofibromatosis, Mibelli's porokeratosis, a late skin porphyria, psoriasis, a vulgar ichthyosis, a tuberous multiple Xanthoma, moniletriks, an inborn pachyonychia, Marfan's syndromes, Peyttsa — Egersa — Touraine, Gardner.
Autosomal retsessivno the enteropatichesky acrodermatitis, full albinism, an inborn dyskeratosis, a dystrophic violent epidermolysis, a verrutsiformny epidermodysplasia, an inborn ichthyosis, a lipoid proteinosis of Urbakh — Vit, Nimann's disease — Peak, an inborn porphyria, a syndrome Grenblad — Strandberg, an inborn polykeratosis of Touraine, Rotmund's syndromes, Verner, a pigmental xeroderma, Blum's syndrome are inherited.
The dominant inheritance linked to a floor (X-chromosome) is observed at an incontience of a pigment (Bloch's type — Sulzberger), a White's atrofiruyushchy disease. The recessive inheritance linked to a floor (X-chromosome) is observed at a dystrophic form of a violent epidermolysis, a diffusion angiokeratoma, a vulgar ichthyosis. With autosomal and dominant inheritance are more numerous, than G. with recessive inheritance. However it is necessary to consider that at the person it is very difficult to track a recessive gene.
Hereditary diseases of skin can be shown right after the birth, in the childhood, youth or even at mature age. Time of emergence of clinical signs of a disease is quite often connected with a mode of inheritance. The same G. can be inherited differently that to a certain extent affects also features of clinical symptomatology, a current and the forecast of a disease. There are observations that is prepotent the inherited forms of diseases quite often are shown by the less clinically expressed frustration and are compatible to life while retsessivno the inherited forms of the same disease are shown by heavier clinical symptomatology. So, e.g., partial albinism is inherited is prepotent, full albinism — retsessivno. At recessive forms of an ichthyosis and violent an epidermolysis and there can be forms, incompatible with life, and dominant forms of the same diseases (a vulgar ichthyosis and a simple violent epidermolysis) proceed is rather good-quality.
G.'s treatment symptomatic. Measures for prevention are recommended by doctors medicogenetic consultation (see).
Separate hereditary diseases of skin — see articles according to names of diseases, syndromes, e.g. Gardner a syndrome, Hartnupa a disease, etc.
Bibliography White G. B. Genetic factors in dermatology, M., 1970; Suvorova K. N. Genodermatoses, p.1 — 2, M., 1969 — 1972; Butter-worth T. S t r e and n L. P. Clinical geno dermatology, Baltimore, 1962; D e s-m o n s F. et WalbaumR. Les affections of cutan£es h6r£ditaires li6es au sexe, Lille m6d., t. 17, p. 447, 1972; N u ne z Andrade R. Genodermatosis, Medicina (Fur.), v. 50, p. 350, 1970; P i fi o 1 A g u a d 6 J. yo. CitogenStica en derma-tologia, Barselona, 1968; Rook A., Wilkinson D. S. a. E b 1 i n g F. J of «G «of Textbook of dermatology, v. 1, p. 40, Oxford — Edinburgh, 1968; T o u r an i n e A., L’h£r£dit£ en m6decine, P., 1955.
H. S. Smelov, S. S. Kryazheva.