FTO and obesity due to melanocortin 4 receptor deficiency: Sex-specific analyses were carried out (data not shown) and variation in the effect of the FTO SNPs on obesity-related quantitative traits by gender was not observed with the exception of higher mean BMI found for African-American females (p = 0.02) but not for males (p = 0.55) with addition of a rs1421085 C allele.