Genetic basis of oculocutaneous albinism

Oculocutaneous albinism (OCA) is generally considered as an autosomal recessive disorder characterized by skin, hair and eye hypopigmentation. Its worldwide prevalence is approximately one out of 20,000. The four OCA types (OCA1–4) are not represented equally in different populations. OCA1–4 are caused by mutations in different genes: TYR in 11q14.3 (OCA1), OCA2 in 15q12 (OCA2), TYRP1 in 9p23 (OCA3) and SLC45A2 in 5p13.3 (OCA4). Molecular analysis of the four genes indicates that some mutations escape detection, and suggests that other OCA genes may exist. The pigmentation phenotype of the patients is largely modified by polymorphisms at a variety of loci throughout the genome, including the OCA loci themselves. OCA stands out as a paradigm of genetic disease influenced by the genetic background.