In addition to constituting a common side effect to antipsychotic treatments with widely used drugs such as risperidone and olanzapine,11 obesity has become a major health problem worldwide, currently affecting nearly 1.4 billion people.18 Interestingly, Ichihara et al.19 found that the 2677G>A/T polymorphism in the ABCB1 gene is associated with increased body mass index (BMI) values in otherwise healthy Japanese individuals. The gene discussed is ABCB1; the disease is obesity due to melanocortin 4 receptor deficiency.