Objective: Osteoporosis is a common disorder with a strong genetic component. Our aim was to investigate the correlation of the estrogen receptor alpha gene microsatellite polymorphism (TA dinucleotide repeat polymorphism 5' upstream of exon 1) with bone mineral density and their relationship to osteoporosis.
Methods: We determined the estrogen receptor alpha gene microsatellite polymorphism using polymerase chain reaction-based microsatellite analysis in postmenopausal Chinese women in Taiwan. Bone mineral density of the lumbar spine and proximal femur were measured using dual-energy X-ray absorptiometry.
Results: The ERalpha genotype was classified into '12' through '27' according to the number of TA dinucleotide repeats they contained, as a 'signpost'. After adjustment for potential confounding factors including age, height, and weight, subjects with genotype 18+ (n=4) had lower bone mineral density values and a 54.5 times greater risk for osteoporosis when compared with subjects with genotype 18- (n=170) at the lumbar spine. This should be interpreted with caution because of the small number of subjects with the unfavorable genotype 18+. According to mean number of TA dinucleotide repeats, women with a high number of repeats (TA > or =20) (n=38) had the lowest bone mineral density and a 6.1 times greater risk for osteoporosis than women with a low number of repeats (TA < or =15) (n=61) at the femoral neck, after adjustment for potential confounding factors such as age, height, and weight.
Conclusion: The present study suggests that the estrogen receptor alpha gene microsatellite polymorphism may be a candidate genetic marker for risk of osteoporosis in postmenopausal Chinese women in Taiwan.