rs1385699

rs1385699 is a missense variant in EDA2R (the X-linked ectodysplasin A2 receptor) producing an arginine-to-lysine substitution at codon 57 (Arg57Lys); the derived 57Lys allele underwent recent positive selection outside Africa. It sits on a haplotype at the AR/EDA2R locus that also carries the strongest common-variant risk alleles for male-pattern hair loss, and because EDA2R signaling participates in hair-follicle development, the variant is a candidate functional contributor to that risk alongside nearby AR variation. Together with the AR variant rs6625163, it is used as one of the major X-chromosome markers for male-pattern hair loss (androgenetic alopecia) tendency.