Association of KIT gene polymorphisms with bone mineral density in postmenopausal Korean women

Bone mineral density (BMD) is a major factor for determining bone strength and osteoporotic fracture risk, and is determined by environmental and multiple genetic factors. KIT, which encodes a transmembrane receptor with tyrosine kinase activity, plays an important role in the differentiation of osteoclasts. We examined the associations between KIT gene polymorphisms and BMD in postmenopausal Korean women. All exons, their boundaries, and the promoter region (approximately 1.5 kb) from 24 individuals were directly sequenced. Eighteen polymorphisms were identified, and three single-nucleotide polymorphisms (SNPs) were genotyped in all study participants (n=946). BMD at the lumbar spine and femoral neck was measured using dual-energy X-ray absorptiometry. The mean age of the study subjects was 58.9+/-7.5 years, and the mean number of years since menopause was 9.6+/-7.9 years. None of the three SNPs (-1694G>T, +41894A>G, and +49512G>A) was significantly associated with BMD value. However, multivariate analysis showed that the ht3 (-1694T-+41894A-+49512G) was significantly associated with lower BMD at the femoral neck (P=0.007 in the recessive model). These findings indicate that KIT-ht3 may be a useful genetic marker for osteoporosis and that KIT may have a role on bone metabolism in humans.