For the pharmacogenetic factors, –759C>T polymorphism of HTR2C gene and 1236C>T, 2677G>T/A, and 3435C>T polymorphisms of ABCB1 gene were not likely to be associated with the susceptibility to overweight/obesity in children and adolescents treated with risperidone. This evidence concerns the gene ABCB1 and obesity due to melanocortin 4 receptor deficiency.