A study of 415 older French women assessed GPR50 polymorphisms (melatonin-related receptor) located on the X-chromosome and found that homozygotes for the minor allele of rs561077 were a risk factor for incident depression in women, but the polymorphisms rs13440581 and rs2072621 were not found to increase risk for depression [14]. The gene discussed is GPR50; the disease is major depressive disorder.