The heterogeneous group of disorders known as oculocutaneous albinism (OCA) 
shares cutaneous and ocular hypopigmentation associated with common 
developmental abnormalities of the eye. Mutations of at least 11 loci produce 
this phenotype. The majority of affected individuals develop some cutaneous 
melanin; this is predominantly seen as yellow/blond hair, whereas fewer have 
brown hair. The OCA phenotype is dependent on the constitutional pigmentation 
background of the family, with more OCA pigmentation found in families with 
darker constitutional pigmentation, which indicates that other genes may modify 
the OCA phenotype. Sequence variation in the melanocortin-1 receptor (MC1R) gene 
is associated with red hair in the normal population, but red hair is unusual in 
OCA. We identified eight probands with OCA who had red hair at birth. Mutations 
in the P gene were responsible for classic phenotype of oculocutaneous albinism 
type 2 (OCA2) in all eight, and mutations in the MC1R gene were responsible for 
the red (rather than yellow/blond) hair in the six of eight who continued to 
have red hair after birth. This is the first demonstration of a gene modifying 
the OCA phenotype in humans.