From a mechanistic perspective, osteocalcin (an osteoanabolic marker) levels were significantly reduced in women with PCOS and BMI < 27 kg/m2 (but not BMI > 27 kg/m2) compared with controls, suggesting that the reduced BMD in lower-weight PCOS may in part be due to reduced bone formation (15). This evidence concerns the gene BGLAP and polycystic ovary syndrome.