Albinism

Albinism (oculocutaneous albinism) is a hereditary defect in the production of melanin, which leads to widespread hypopigmentation of the skin, hair and eyes; Deficiency of melanin (and, consequently, depigmentation) can be complete or partial, but all skin areas are affected. Eye damage causes strabismus, nystagmus and visual impairment. The diagnosis is usually obvious, but a vision test is needed. There is no effective way to treat, except to protect the skin from sunlight.

There are 2 forms of albinism: the eye, the eye. The oculopoietic form can be tyrosine-negative or tyrosinase-positive and is inherited by an autosomal recessive type linked to the X chromosome.

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Oculomotor albinism

Tyrosine-negative albinism

These albinos do not synthesize melanin, which is manifested by blond hair and very pale skin.

Iris is transparent, transillumination, a symptom of "pink" eyes.

Ocular fundus

• Absence of a pigment with suspiciously large choroidal vessels.
• Hypoplasia of vessels of perimacular arcades.
• Hypoplasia of the fovea and optic nerve.
• Refractive anomalies, visual acuity <б / 60.

Nystagmus, as a rule, pendulum horizontal, intensifying in bright light. The amplitude decreases with age.

Chiasma with a decrease in the number of crossed fibers. Pathology of the visual pathways: from the lateral geniculate body to the visual cortex.

Tyrosinase-positive albinism

With this form of albinism, a different amount of melanin is synthesized, hair and skin color can range from very light to normal.

• Iris blue or dark brown, transillumination.
• An ophthalmic fundus with a different degree of hypopigmentation.
• Visual acuity is reduced due to fovea hypoplasia.

Associated syndromes

• Cbediak-Higashi syndrome is an abnormality of leukocytes, manifested by relapsing purulent infections and early death.
• the Hermansky-Pudlak syndrome is a lysosomal disease of the accumulation of the reticuloendothelial system, characterized by a tendency to hematomas due to platelet dysfunction.

Eye albinism

Ophthalmic albinism is manifested by a predominant eye damage with less noticeable changes in the skin and hair color.

The type of inheritance of eye albinism - linked to the X-chromosome, less often - autosomal recessive.

Female carriers are asymptomatic, with normal eyesight, a partial transillumination of the iris and a fine dispersed zone of depigmentation and granularity of the pigment at the middle periphery. Male patients with hypopigmented iris and eye fundus.

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Forms of albinism

Oculocutaneous albinism is a group of rare hereditary disorders in which melanocytes do not produce melanin or produce in insufficient quantities, resulting in pathologies of the eyes and skin. Albinism of the eyes - reduction of retinal pigmentation, strabismus, nystagmus, deterioration of visual acuity, monocular vision. These disorders occur due to pathology of the visual tract of the central nervous system. Albinism of the eyes can occur in addition to skin lesions.

There are four main genetic forms of affinity, which have a variety of phenotypes. All forms are autosomal recessive.

Type I is caused by absence (type IA; 40% of all cases) or insufficient quantity (type IB) of tyrosinase. Tyrosinase catalyzes some stages in the synthesis of melanin.

Type IA - classic tyrosinase-negative albinism: skin and hair are milky-white, eyes - blue-gray.

Type IB - a violation of pigmentation can be pronounced or slightly noticeable.

Type II (50% of all cases) occurs due to mutation of the P gene. The P protein function has not yet been studied. The range of phenotypes of pigmentation disorders varies from minimal to moderate. With solar exposure, the formation of pigmented nevi and lentigo can occur, which can increase and darken.

Type III occurs only in black patients. This is caused by mutations of tyrosinase-bound protein in the gene, which is responsible for the synthesis of melanin. The skin is brown, the hair is red.

Type IV is an extremely rare form in which a genetic defect is found in a gene that encodes protein transport.

In the group of hereditary diseases, oculocutaneous albinism is accompanied by increased bleeding. With Chediak-Higashi syndrome, the number of platelets decreases, resulting in hemorrhagic diathesis. Patients develop an immunodeficiency state due to a violation of the granularity and structure of leukocytes. Progressing neurologic degeneration develops.

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How to recognize albinism?

The diagnosis of all types of albinism is obvious when examining the skin, but it is necessary to make sure that the iris is translucent, reducing retinal pigmentation, reducing visual acuity, and disturbing eye movement (strabismus and nystagmus).

Treatment of albinism

There is no treatment for albinism. Patients are at risk for developing skin cancer and should avoid sunlight, wear sunglasses with ultraviolet filtration and use sunscreen with SPF> 30