The skin contains a number of pigment cells called melanocytes, and the color of it does not depend on numbers but on how they work.
The color of the skin has a protective function because melanin absorbs ultraviolet light, which although necessary, in excessive amounts is harmful.
This condition determines and allows different races living in their home, for example, dark skin living in Africa or in very hot, a defense against intense solar radiation, while in Scandinavian countries other areas where less light reaches ultraviolet light skin can get all you need for your body to make vitamin D.
Melanin is the end product of a complex series of chemical reactions and can not be formed without the presence of an enzyme called tyrosinase.
But worldwide there are people with white skin, as well as hair and eye iris, this feature is known as albinism, which comes from the Latin word albus which means white and this is because albinos are not genetically encoded to produce tyrosinase and thus melanin.
This disease affects roughly one in every 20,000 people of all races, is hereditary and occurs because the eyes, skin and / or hair pigment containing less than usual or total lack of it. When there is a total lack of pigment, stressed skin and white hair and pink eyes.
One form is the type of ocular albinism affecting only the eyes, showing the pigmentation of skin and hair a normal state. In severe cases of albinism, the central area of vision, the macula does not develop properly, leading to a large decrease of vision.
A second rare form of albinism is associated with increase bleeding tendency and gets infections.
