FTO and obesity due to melanocortin 4 receptor deficiency: It has been evidenced that single nucleotide polymorphism (SNP) rs1121980 in the FTO gene is also related to an increased risk of class II (BMI 35.0–39.9 kg/m2) and III (BMI ≥ 40.0 kg/m2) obesity in women in the Mexican population [10].