Angelman syndrome
The OCA2 gene is located in a region of chromosome 15 that is often deletedin individuals with Angelman syndrome. A loss of this gene does not cause thecharacteristic neurologic features of Angelman syndrome; however, people withthis condition who are missing one copy of the OCA2 gene tend to have unusuallylight-colored hair and fair skin. Cells with only one copy of the OCA2 gene make areduced amount of P protein compared with cells with two functional copies of thisgene, which affects the coloring of the hair and skin.
A small percentage of people with Angelman syndrome also have oculocutaneousalbinism type 2. This condition occurs when people have two nonfunctional copies ofthe OCA2 gene in each cell. In addition to a deletion in chromosome 15 that removesone copy of the OCA2 gene, these individuals have a mutation in the OCA2 geneon the other copy of chromosome 15. As a result, cells make little or no functionalP protein. A lack of P protein disrupts the production of melanin, leading to thecharacteristic features of albinism