Type 1 oculocutaneous albinism (OCA1) describes a group of tyrosine related OCAs (see this term) that includes OCA1A, OCA1B, type 1 minimal pigment oculocutaneous albinism (OCA1-MP) and type 1 temperature sensitive oculocutaneous albinism (OCA1-TS) (see these terms).
The worldwide prevalence of OCA1 is estimated at 1/40,000.
The phenotypic spectrum seen in OCA1 is variable. Pigmentation present in the skin, hair and eyes can range from little or none to pigmentation localized only to the peripheries. Findings of nystagmus, photophobia and reduced visual acuity are often present.
OCA1 is caused by a mutation in the TYR gene located on chromosome 11q14.2 encoding tyrosinase. Mutations in OCA1A and OCA1B lead to a total or partial loss of the catalytic activity of tyrosinase while those in OCA1-MP and OCA1-TS lead to minimal activity or temperature sensitive tyrosinase proteins.
The different forms of OCA1 are all transmitted autosomal recessively so genetic counseling is possible.