For example, FTO loci are associated with an adipocyte thermogenesis regulation pathway involving IRX3 and IRX5,53 and BDNF is associated with physical activity.54,55 Given that the mechanism governing the effects of genes on obesity remains poorly understood, further studies are required to clarify the genetic associations with obesity. The gene discussed is BDNF; the disease is obesity due to melanocortin 4 receptor deficiency.