Therefore, we performed agenome-wide association study (GWAS) of circulating leptin levels from 32,161individuals and followed up loci reachingP<10−6 in 19,979 additional individuals.We identify five loci robustly associated (P<5 ×10−8) with leptin levels in/near LEP,SLC32A1, GCKR, CCNL1 and FTO. Although theassociation of the FTO obesity locus with leptin levels is abolished byadjustment for BMI, associations of the four other loci are independent ofadiposity. The gene discussed is GCKR; the disease is obesity due to melanocortin 4 receptor deficiency.