In this age-matched analysis from Bulgaria of 40 women with PCOS without obesity, 20 women with PCOS and obesity (BMI > 30 kg/m2), and 20 control women with obesity alone, FGF23 levels (and serum calcium, parathyroid hormone [PTH], vitamin D, receptor activator of nuclear factor kappa-B ligand [RANKL] and osteopontin) were similar between the PCOS and non-PCOS groups (70). The gene discussed is TNFSF11; the disease is obesity due to melanocortin 4 receptor deficiency.