Increased level of C-terminal telopeptides of type I collagen (CTX, bone resorption marker) and decreased level of alkaline phosphatase (ALP, bone formation marker) were found in patients with comorbidity of PCOS and PDD than in patients with PDD alone (31), suggesting that PCOS worsens the bone metabolism of the alveolar bone around the periodontal tissue. Here, CYP27A1 is linked to polycystic ovary syndrome.