11 April

Albinism in people - types , features , inheritance

Contents:

1. Types and symptoms of albinism in humans

2. Causes and types of its inheritance

3. Treatment of diseases

4. Albinism in

children

Albinism - a rare genetic disorder in which the completely or partially missing melanin - the pigment that is in the skin, hair, iris and paints them in a certain color.

Types and symptoms of albinism in humans

There are two types of albinism in humans: Oculocutaneous and eye.Oculocutaneous albinism is the most common and manifests itself with one of the following subtypes:

1. Oculocutaneous albinism 1 (HCA 1), among which are the HCA 1A - pigment melanin is completely absent and the HCA 1B - pigment is produced in insufficient quantities.Symptoms of albinism type 1A HCA:

  • white hair;
  • milky white skin is dry;
  • impaired sweating;
  • translucent blue iris, which eventually becomes pink or red color (due to the translucent blood vessels);iris darkens with age;
  • absence of any pigment changes in the skin;
  • low visual acuity;
  • skin is not able to sunbathe, with prolonged contact with sunlight burns occur.

signs of albinism HCA 1B:

  • hair is white, but with age, acquiring a yellowish tinge;
  • white eyelashes, but darken with age;
  • iris with age becomes brown or light brown color;
  • visual acuity is low, but can increase with age;
  • present pigmentation of the skin (from mild to almost normal).

In some cases, albinism in humans is temperature sensitivity, which manifests itself in the form of increased pigmentation on the "cold" areas of the body (hands, feet), and its absence in the areas of "warm" (armpits, head, eyes).Thus, the hair on hands can be dark and light color remains.

2. Oculocutaneous albinism 2 (2 HCA).The most common type in the world, its symptoms are highly variable, what is not the last role played by the human race belongs.Among them:

  • different manifestation of pigmentation from its complete absence to nearly normal expression;
  • even in the absence of pigmentation, it may appear with age;
  • poor eyesight, but improves with age;
  • hair yellow (for blacks), pale yellow or reddish tinge (the Europeans);slightly darken with age;
  • skin white (regardless of race);
  • iris blue-gray color of different saturation (regardless of race);
  • in areas that come into contact with sunlight pigmentation can appear in the form of age spots and freckles.

3. Oculocutaneous albinism 3 (3 HCA).The third type of albinism Oculocutaneous in children and adults is quite rare.Such people are very different from the "classic" albino.In particular, the characteristic features of this type of albinism is:

  • light brown or reddish-brown skin;
  • light brown or reddish hair;
  • brown-blue irises;
  • visual pathology are less pronounced than in other types of albinism.

Ocular albinism little visible externally.Leather, human hair looks a little lighter than the relatives.Signs of this type of albinism in most cases are only in ocular pathologies.In principle, the eye disease is a characteristic feature of any type of albinism.People albino reduced visual acuity, it is usually accompanied by nystagmus - bouncing movements of the eyeballs.Most often accompanied by strabismus albinism often - farsightedness, nearsightedness, astigmatism.Ocular albinism sick men, women are only carriers.Men ocular albinism is inherited, with all its features, meanwhile, women are only present some pigmented fundus changes.

Causes and types of its inheritance

Tyrosinase - an enzyme by which melanin is synthesized.As a result of the blockade or the complete absence of this enzyme is no formation of melanin, there albinism.Tyrosinase is the causative mutation at the gene level, whereby it is not produced at all, or is made in insufficient quantities.The lack of tyrosinase can be caused by a mutation of the gene coding for it (at 1 HCA), which leads to the cessation of its production.When HCA 2 tyrosinase does not vary, but there is a mutation of the gene encoding the P protein, which causes its blockade.When HCA 3 undergoes mutations TRP-1 protein, which is responsible for the production of black melanin.His mutation leads to disruption of the tyrosinase production, resulting in melanin changes color from black to brown.

Oculocutaneous albinism is inherited as an autosomal recessive and autosomal dominant.Depending on the type of inheritance distinguished: total, partial and partial albinism.

1. by rigorous albinism is inherited in an autosomal recessive, which means that albinism in children can occur only if the father and mother are carriers of the defective gene.

2. Partial albinism is inherited in an autosomal dominant manner, that is, to ensure that the disease manifested in the child only one defective gene is inherited from one parent.There are cases of autosomal recessive inheritance of partial albinism.

3. Partial albinism is inherited in an autosomal dominant only.

Ocular albinism is X-linked recessive inheritance.This means that this type of disease are sick men, women are only the carriers.

Treatment of diseases

No regimens of albinism in humans to date does not exist.It is possible to partially remove some of the consequences of the disease, in particular, problems with vision, but to treat it useless.Albinism in humans suggests a greater likelihood of skin cancer, so patients should avoid prolonged exposure to the sun, and enjoy the light-shielding means, if necessary.

Albinism children

Unfortunately, albinism sick child often becomes an outcast in society.Nevertheless, these kids absolutely do not differ from healthy children.With the right approach to their education, including full-fledged members of society grow.There is no need to do this from the child's unusual.

Albinism in children is not a contraindication for walking in a normal kindergarten, regular school.Intelligent data of healthy children and children with albinism are not different.The only difference - is a specific appearance (which, incidentally, makes such an unusually beautiful children) and vision problems.The latter can be solved with the help of glasses and contact lenses as well as sitting on the front desks.In some cases, to eliminate eye pathologies require surgery, sometimes with age, vision gradually improved without interference.

absence of melanin in the skin of an albino child makes it very sensitive, so the house must be a special sunscreen, sunglasses and other accessories.

Attention!

This article is available exclusively in the educational purposes and is not research material or professional medical advice.

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