Several pathophysiological mechanisms seem to be implicated in the association between PD and osteoporosis and reduced BMD, and these include: female gender, vitamin D deficiency, reduced exposure to sunlight, low body weight, nutritional status, vitamin B12, folate deficiency and hyperhomocysteinemia, PD duration and severity, immobility, decreased muscle strength and other neuroendocrinal status (e.g., increased serum concentration of under-carboxylated osteocalcin) (155, 157). Here, BGLAP is linked to Parkinson disease.