“…Genetic factors play important roles in the pathogenesis of osteoporosis (Albagha and Ralston, 2006;Ferrari, 2008;Cheung et al, 2010;Hosoi, 2010;Ralston, 2010;Feng et al, 2012;Woo et al, 2012;Zhang et al, 2013). Previous studies have indicated several genes associated with BMD and osteoporosis, such as the osteoprotegerin (OPG) gene (Pocock et al, 1987;Hofbauer and Schoppet, 2002;Langdahl et al, 2002;Yamada et al, 2003;Arko et al, 2002Arko et al, , 2005Vidal et al, 2011;Feng et al, 2012;Hussien et al, 2013;Zhang et al, 2013), the estrogen receptor alpha gene (Kurt et al, 2012), and the vitamin D receptor (VDR) gene (Fang et al, 2005;Jakubowska-Pietkiewicz et al, 2012;Kurt et al, 2012;Li et al, 2012;Hussien et al, 2013;Horst-Sikorska et al, 2013). OPG has been considered one of the most important candidate genes for BMD and osteoporosis among these genes.…”