Several GWAS of body mass index (BMI) and/or obesity have been performed, and the first wave resulted in the suggestion of SNPs in/near the INSIG2[4], FTO[5], PFKP[6], and CTNNBL1[7] genes, however, only SNPs in the FTO locus were convincingly replicated in other GWAS [6], [8] and independent replication studies [9]–[11]. The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.