The authors showed that the X12Ala variant (Pro12Ala or Ala12Ala) is significantly associated with greater insulin sensitivity in childhood obesity, which may, therefore, be protected against cardiovascular disease, obesity, and diabetes due to the phenotypic effect of the Ala 12 allele on insulin resistance [101]. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.