Objective: To investigate the relationships between --1997G/T polymorphisms in collagen I alpha 1 gene (COL I A1) upstream regulatory region and bone mineral density(BMD) in postmenopausal women.
Methods: There were 318 voluntary subjects in Chengdu city enrolled (212 osteoporotic postmenopausal women and 106 normal control subjects) and their BMD were measured by dual-energy X-ray absorptiometry (DEXA ) at lumbar spine (L2-L4). 2 mL peripheral blood was drawn and genomic DNA was extracted from white blood cells. Specific fragment which includes the objective gene was amplified by polymerase chain reaction (PCR); the genotypes of --1997G/T site in COL I A1 were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The PCR products were digested with restriction endonuclease Eco31 I and the result was observed by agarose gel electrophoresis.
Results: In the osteoporotic postmenopausal women group, 82 GG, 99 GT and 31 TT were found. In the normal control group, the number of GG, GT and TT were 51, 45 and 10. The subjects in osteoporotic group had higher T allele frequencies than those in normal control group (P < 0.05). In the osteoporotic postmenopausal women, the carriers with TT genotype of -1997G/T polymorphism had lower spine BMD than those with GG genotype or GT genotype (P < 0.05).
Conclusion: There is a correlation between -1997G/T polymorphisms in COL I A1 upstream regulatory region and BMD. The TT genotype individuals have lower BMD than other genotype individuals.