ENPP1 and obesity due to melanocortin 4 receptor deficiency: In both studies, we genotyped six SNPs that are known to be associated with risk of obesity in European populations: rs17782313 near MC4R[6]; rs2815752 near NEGR1[7]; rs7754561 near ENPP1[8]; rs1805081 in exon 6 of NPC1[9]; rs10938397 near GNPDA2[7] and rs1421085 in intron 1 of FTO[10].