Estimation of carrier frequency of a 2.7 kb deletion allele of the P gene associated with OCA2 in African-Americans

Oculocutaneous albinism (OCA) is a heterogeneous genetic disorder characterized by hypopigmentation of the hair, skin, and eyes and is associated with the ocular features of nystagmus, reduced visual acuity, and misrouting of the optic fibers at the chiasm. OCA1 or tyrosinase-related OCA results from mutations of the tyrosinase gene on chromosome 11q. OCA2 or P related OCA results from mutations of the P gene on chromosome 15q that encodes a 110 kDa integral melanosomal membrane protein. OCA2 is the most common form of albinism, especially among African-Americans and Africans. In a previous study, we found a 2.7 kb deletion allele that included a single exon of the P gene. To measure the frequency of this mutation, we tested a set of 470 newborn screening (NBS) filter blood spots collected from African-Americans born over a 1-week period in Michigan using a PCR assay. Two individuals from this population were found to carry the 2.7 kb deletion allele.