Albinism
Albinism is a congenital disease. This disease Albinism in vzroslyhpodrazumevaet absence in the skin, hair, nails, pigment and iridescent eye shells of the pigment melanin. The name "albinism" comes from the Latin "albus", which in Russian means "white." This disease is known a long time, as his descriptions are even found in the documents of ancient Rome and Greece.Causes of albinism
Albinism arises because of the lack of the enzyme tyrosinase, or blockade. It is extremely important for melanin production (the name comes from the Greek word "melanos", which in Russian means "black"). Skin color is determined by the amount of melanin in it. What it is, the darker the skin. In those cases where problems with development of tyrosinase is observed, cause of albinism is considered to be a mutation in the genes. Albinism is inherited from parents. He appears in a child if both parents are carriers of the defective gene. When the defective gene is present in only one parent, albinism does not develop in children, but the body is still a mutated gene that can be passed to the next generation. This whole process is called autosomal recessive inheritance.Types of albinism
Albinism is divided into three types:- total;
- incomplete;
- partial.
Partial albinism, which is also called piebaldizmom also evident from birth. Sometimes it can be a symptom syndromes Klein-Waardenburg, Chedaka-Higashi, Mende, Cross-MakKyuzika-Breen, Tietze, Hermanski-Pudlaka. Typical manifestations are achromia areas with clear boundaries, but the irregular shape on the surface of which there are small specks of dark brown color. In general, partial albinism in humans occurs on the face, legs and abdomen, as well as the hair strands Aged color. At these spots close to the skin of increased pigmentation is often observed. This type of albinism is inherited in an autosomal dominant manner.
Incomplete albinism, which is also called albinoidizmom appears only hair hypopigmentation, iris eyes and skin. Very rarely observed photophobia. The reason is the low activity of tyrosinase, but its synthesis is not blocked. Partial albinism is inherited in an autosomal dominant manner, at least - recessive.
Also distinguish the eye and skin and ocular albinism (xanthochromism). The cause is xanthochromism mutation in one of the 4 genes. Signs of the variety of albinism are skin, hair pigmentation, pigmentation of the iris eye and vision problems. Divided into four types:
- Type 1 occurs due to mutations in the eleventh chromosome. This type of albinism in humans arises from birth. Skin and hair color of milk sick, and his eyes - blue. Sometimes age can begin to make melanin: the eyes and the skin becomes slightly darker.
- Type 2 occurs due to mutations in the fifteenth chromosome. The skin is white or light brown hair - yellow, reddish or golden brown eyes have a yellowish-brown or blue-gray color. Basically ill residents of the Sahara Desert, African Americans and Indians living in North America. Under the sun on the skin almost instantly appear freckles.
- 3 type provoking mutation in the ninth chromosome. It is very rare. The skin is brown with a reddish tinge, his eyes - red hair has a red tint. Basically ill people living in southern Africa.
- Type 4 is also extremely rare and is caused by a mutation in the fifth chromosome. Ill mostly people living in south-east Asia. The symptoms are the same as the second type.
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