albinism is the lack of the production of
People with this form of albinism have white hair, light-colored eyes, and very pale skin that does not tan. Other mutations in the TYR gene reduce but do not eliminate tyrosinase activity. These mutations, which allow some melanin to be produced, cause oculocutaneous albinism type 1B (OCA1B). from Wikipedia, the free encyclopedia. Albinism is a lack of pigmentation in the eyes, skin and/or hair. Albinism is an inherited condition resulting from the combination of recessive alleles passed from both parents of an individual. This condition is known to affect mammals, fish, birds, reptiles, and amphibians. Animals in some areas have extremely high rates of albinism. In Marionville, for example, white squirrels dominate the population. The number of these partial albinos remains high because people living there feed and pamper their white squirrels and have passed ordinances to protect them from hunters and motorists. Albinism is caused by a mutation in one of several genes. Each of these genes provides instructions for making one of several proteins involved in the production of melanin. Melanin is produced by cells called melanocytes, which are found in your skin and eyes. oculocutaneous albinism. More than 100 mutations in the TYR gene have been identified in people with oculocutaneous albinism type 1. These mutations disrupt the normal production of melanin, which reduces coloring of the hair, skin, and eyes and causes problems with vision. Albinism includes a group of inherited disorders that are characterized by little or no production of the pigment melanin. The type and amount of melanin your body produces determines the color of your skin, hair and eyes. Causes of albinism. Albinism is caused by a lack of the pigment melanin, which gives hair, skin and eyes their colour. Melanin is also involved in the development of the retina (the thin layer of nerve cells that line the inside of the back of the eye) and nerve connections between the retina and the brain, which is why most people with albinism have vision problems. The following is a brief overview of the current classification of albinism. OCA is characterized by the reduction or absence of melanin in the skin, hair, and optic system (including the eyes and optic nerves). The lack of skin pigment results in a pale skin appearance and an increased risk of skin cancer. As shown in Table 1, OCA is divided further into several subtypes based on the distinct genetic mutation. Table 1. Oculocutaneous Albinism Types (Open Table in a new window) Albinism consists of a group of inherited abnormalities of melanin synthesis and are typically characterized by a congenital reduction or absence of melanin pigment. Albinism results from defective production of melanin from tyrosine through a complex pathway of metabolic reactions. Only a small percentage of animals carry the recessive gene, so the chance of the pairing of recessive genes in an individual animal is slight. In humans, for example, about one in 70 people carry a recessive gene for albinism, and about one in 20,000 humans are albinos. At least 300 species of animals in North America have albino individuals.
Melanin