MC1Rgenen

MC1R, short for melanocortin 1 receptor, is a gene that encodes a G protein-coupled receptor expressed primarily on the surface of melanocytes in the skin and hair follicles. The receptor binds peptide hormones such as alpha-melanocyte-stimulating hormone (α-MSH) and adrenocorticotropic hormone (ACTH). When activated, MC1R signals through the Gs protein to raise intracellular cAMP levels, influencing the cellular programs that control pigment production.

In pigmentation, MC1R activity promotes the synthesis of eumelanin, the dark pigment that provides some protection against UV radiation. Reduced or altered MC1R signaling shifts melanin production toward pheomelanin, the lighter red-to-yellow pigment, contributing to lighter skin, freckles, and red hair in many individuals. The exact phenotype depends on the combination of MC1R variants and other genetic factors.

Genetic variation in MC1R is common in humans and contributes to broad differences in pigmentation. Several variants are associated with lighter phenotypes, particularly in European populations. Notable examples include R151C, R160W, and D84E, among others such as V60L and V92M. These variants can range from partial loss of function to more substantial impairment of receptor signaling, influencing an individual’s pigmentation and tanning response.

Clinically, MC1R variants are linked to an increased risk of UV-induced skin damage and melanoma independent of visible skin color or hair type in some studies. The penetrance and effect size of specific variants vary by population. MC1R continues to be studied for its roles beyond pigmentation, including potential influences on inflammation and other physiological responses.

Location-wise, the MC1R gene is located on chromosome 16q24.3. Evolutionary pressures related to UV exposure have shaped MC1R allele frequencies across human populations.