Some possible factors could be the G allele of the OPG rs2073618 (1181 G/C) SNP favouring lumbar spine bone loss in osteoporosis, or the G allele of the OPG rs3134070 (245 T/G) and rs3102735 (163 A/G) favouring cortical bone loss in PHPT. The gene discussed is TNFRSF11B; the disease is osteoporosis.