Relationships between the insulin-like growth factor I (IGF-I) receptor gene G3174A polymorphism, serum IGF-I levels, and bone mineral density in postmenopausal Korean women

We investigated the relationships between the IGF-I receptor gene G3174A polymorphism, serum IGF-I levels, and bone mineral density (BMD) in postmenopausal Korean women. The IGF-I receptor gene G3174A polymorphism was analyzed in 367 postmenopausal Korean women. Serum levels of IGF-I, bone turnover markers (osteocalcin, bone alkaline phosphatase, carboxy-terminal cross-linking telopeptide of type I collagen), and BMD at the lumbar spine and proximal femur were measured. The frequencies of the AA, GA, and GG genotypes were 10.9%, 44.1%, and 45.0%, respectively. BMD at the lumbar spine was significantly higher for the AA genotype than the other genotypes and showed an A allelic dose effect; however, no significant differences in BMD were observed at the proximal femur with respect to genotype. No differences were noted between the three genotypes in terms of serum levels of IGF-I or bone turnover markers. Women with low BMD showed a lower prevalence of the AA genotype and A allele than age-matched women with normal BMD. Women with the AA genotype were found to have about half the risk of a low BMD than women with other genotypes. In conclusion, IGF-I receptor gene G3174A polymorphism is associated with lumbar spine BMD in postmenopausal Korean women.