#genetics - anomalies in melanin production: albinism, heterochromia and others.

Melanocytes are specialized cells that produce melanin, a pigment of dark brown coloration. These cells are found in the skin and retina. The color of the hair, for example, is determined by the melanocytes activity, producing melanin from the amino acid tyrosine. The addition of another amino acid known as cysteine produces a yellow pigment called pheomelanin. The ratio of the pigment melanin and pheomelanin gives rise to the various hairs colors. 

Genetic abnormalities related to the production of melanin can cause disorders and diseases such as albinism, melanism, heterochromia, piebaldism, among others. 

Albinism: is the genetic abnormality in which an enzimatic defect in the production of melanin resuls in total or partial lack of pigmentation of the skin, eyes and hair. Albinism can be associated with vision defects, such as photophobia, nystagmus and astigmatism. Lack of skin pigmentation makes the organism more susceptible to sunburns and skin cancer. 

Melanism: In this case the opposite occurs, ie, animals and plants carrying this anomaly produce a greater amount of melanin, in a disorderly manner. 

Heterochromia: is a genetic abnormality in which the individual has eyes in different colors. This is due to a change in EYCL3 and EYCL1 genes located on chromosome 15, which encode the amount of melanin present in each eye. It also occurs in animals, such as dogs and cats. 

Piebaldism: is a rare autosomal dominant disease caused by an irregular development of the melanocytes in the embryonic period. White hair forelock (poliosis) and a triangular depigmentation area located centrally on the forehead are clinical findings suggestive of the disease.