Several studies have demonstrated a negative correlation between obesity and the levels of free testosterone, bioavailable testosterone (free and albumin-bound), and total testosterone (free, bioavailable, and bound to sex-hormone-binding globulin [SHBG]), which is maintained in all age groups [3,4,5,6,7]. The gene discussed is SHBG; the disease is obesity due to melanocortin 4 receptor deficiency.