In 2007, FTO (fat mass and obesity-associated gene) was first discovered in a genome-wide association study (GWAS) for type 2 diabetes [4], and, almost simultaneously, two other teams independently reported that the FTO gene was associated with obesity (or obesity-related traits) in a GWAS and a genetic association study [5,6]. The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.