Clearly, it is not negligible that in these conditions of obesity/overweight, an increase in the adipose content ultimately also means a greater share of active aromatase enzyme and consequently a greater share of free estrogenic hormones potentially stimulating and proliferating on the mammary gland or on the other hormonally sensitive areas. The gene discussed is CYP19A1; the disease is obesity due to melanocortin 4 receptor deficiency.