CCNL1 and obesity due to melanocortin 4 receptor deficiency: 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.