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A genetic condition that is inherited, albinism is a reduction in melanin pigment in the hair, skin and eyes. This inherited condition can occur in all ethnicities and races, and is found throughout the globe. In America, the rate of albinism is estimated at 1 in 20,000 people, and included in this are the variant forms of albinism. In some places around the world, the rate can be as high as 1 in 3000.
Generally speaking, an albinism trait is inherited from both parents, where the parents are carriers of the trait without the actual disorder. When parents both carry the gene for albinism, each pregnancy has a one in four chance of producing albinism. Even though albinism is known to be an inherited genetic disorder, there is so far no way of testing parents to see if they carry the trait. This is because the changes in the DNA relating to albinism are not always located in the same place. If the parents have had a previous child with albinism, it is possible to predict whether or not a subsequent pregnancy will result in another child with the disorder.
Seven Types of Albinism
There are two main types of albinism, with 5 further classifications. Ocular albinism (referred to as OA) is a lot less common than the other forms, and it only affects the eyes. The hair and skin may appear a bit lighter than others in the family, but it is still pigmented. Oculocutaneous albinism (OCA) is the more common form, with many variations, and this affects the skin, eyes and hair. OCA can be further classified into the following:
OCA1 (tyrosinase-related albinism)
This form of albinism is due to a genetic defect in tyrosinase, an enzyme that assists with changing tyrosine into pigment. These albinos usually have very pale skin and white hair.
OCA2 (P gene albinism)
OCA2 is a genetic defect in P protein, which assists with the function of the tryosinase enzyme. People with this form of albinism have some color pigmentation in their hair, which can range from light blond through to shades of brown.
This form is less common and is due to a genetic defect in TYRP1, which is a protein. This protein relates to tryosinase, and unlike other forms, people with OCA3 can have good pigment and be less recognizable as albino.
This is also due to a protein genetic defect. Pigment production is similar to those with OCA2.
These variations were only discovered in humans from 2012-2013, and are considered to be uncommon.