CYP1A2 expression appeared to be in no association with obesity (P > 0.1); furthermore, the frequency of patients with obesity was similar in the groups of patients expressing CYP3A4 at normal/high and low levels (18.5% of CYP3A4 normal/high expressers, 18.2% of CYP3A4 low expressers, Wald ChiSq = 0.1, N = 87, P = 0.98). This evidence concerns the gene CYP3A4 and obesity due to melanocortin 4 receptor deficiency.