ESR1 and osteoporosis: Genes relevant to bone metabolism and disease genes of rare monogenic bone diseases are widely studied by this approach and the association with osteoporosis has been reported in many genes; however, only a few genes like those for estrogen receptor 1 (ESR1), α1 chain of type I collagen (COL1A1) and low-density lipoprotein 5 (LRP5) are replicated for their association [3]–[5], including large-scale meta-analyses using different ethnic populations [6], [7].