The ALUI calcitonin receptor gene polymorphism (TT) is associated with low bone mineral density and susceptibility to osteoporosis in postmenopausal women.

Osteoporosis is a common disorder with a strong genetic component. Our aim was to evaluate the correlation of the ALUI calcitonin receptor gene polymorphism to bone mineral density and their relationship to osteoporosis. We determined the ALUI calcitonin receptor gene polymorphism using polymerase chain reaction-based restriction analysis in 167 postmenopausal women in Taiwan. The polymorphism was detected by the restriction enzyme ALUI, where the C allele indicated the absence of the cuttable site and the T allele indicated its presence. Bone mineral density of the lumbar spine and proximal femur were measured using dual-energy X-ray absorptiometry. The allelic frequencies for the 167 postmenopausal women in Taiwan were 86.5% for C and 13.5% for T in ALUI restriction fragment length polymorphisms. The prevalence of each genotype in the study population was 2.4% TT, 22.2% CT, and 75.4% CC. The three genotypic groups differed significantly in unadjusted and adjusted bone mineral density at the lumbar spine and the femoral neck. Unadjusted and adjusted bone mineral density values were lowest in women with the TT genotype. The ALUI calcitonin receptor genotype showed a positive association with prevalence of osteoporosis in the subjects. That is, women with genotype TT had a greater risk for developing osteoporosis at the lumbar spine and at the femoral neck. The ALUI calcitonin receptor gene polymorphism is associated with reduced bone mineral density and predisposes women to osteoporosis, but should be interpreted with caution because of the small number of subjects in the unfavorable TT genotype.