Phenotypic Expression of Melanocortin-1 Receptor Mutations in Black Jamaicans

The melanocortin-1 receptor (MC1R) gene is the only gene identified that explains substantial variation in hair color (i.e., that within the normal population). In northern European populations the majority of red-haired persons are homozygous for a limited number of mutations that diminish signaling through the G coupled protein receptor encoded by the MC1R gene (Valverde et al, 1995). A clear heterozygote effect is seen on freckling, sun sensitivity, and risk of skin cancer (Healy et al, 2000;Palmer et al, 2000), and a minority of individuals with red hair are heterozygotes rather than homozygotes (or compound heterozygotes) for MC1R mutations (Flanagan et al, 2000). Although there has been interest in studying the evolution of the MC1R, and populations from Africa and Asia have been sampled as part of such work, study of the genotype/phenotype relationship has been limited to European-derived populations. We recently had the opportunity to study persons with red hair but who self-identify themselves as black.