Association of insulin-like growth factor I gene polymorphisms with the risk of osteoporosis in a Chinese population

Osteoporosis is a systemic metabolic and serious skeletal disease commonly observed among the elderly. Insulin-like growth factors (IGFs) are critical regulators for bone cell function. We estimated the role of IGF-I rs35767, rs2288377 and rs5742612 polymorphisms in the susceptibility to osteoporosis in a population of China, and assessed gene-environment interactions. A total of 346 patients with osteoporosis and 346 controls were enrolled. Genotyping of IGF-I rs35767, rs2288377 and rs5742612 was amplified and performed with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The TA and AA genotypes displayed elevated risk of developing osteoporosis (TA vs TT: OR=1.54, 95% CI=1.11-2.15; AA vs TT: OR=3.65, 95% CI=2.09-6.37). Compared with TT individuals, individuals with the TA+AA genotype had a substantial increased susceptibility to osteoporosis (OR=1.80, 95% CI=1.31-2.46). In recessive model, the AA genotype of rs2288377 displayed 2.89 folds risk of osteoporosis (adjusted OR=2.89, 95% CI=1.70-4.89). A significant negative interaction was found between IGF-I rs2288377 and BMD levels for femoral neck (r=-0.14, P<0.001), total hip (r=-0.09, P<0.001) and trochanter (r=-0.13, P<0.001). In conclusion, we suggest that IGF-I rs2288377 polymorphism had a strong influence on osteoporosis susceptibility in this Chinese population.