Therefore, FTO polymorphisms association with obesity alters the expression of the IRX3 gene in the human brain which is closely related to the regulation of obesity and its risk factors.55 However, more functional studies are required to confirm the role of FTO protein in obesity which is not completely elucidated whereas, the animal studies suggested that FTO expression is regulated by fasting and feeding habits.54 This evidence concerns the gene IRX3 and obesity due to melanocortin 4 receptor deficiency.