Estrogen receptor-1 genotype is associated with bone structure in premenopausal obese women

Estrogen action in bone is mediated mainly by estrogen receptor alpha (ESR1). Bone mineral content of the lumbar spine and left proximal femur and the femoral neck structure was measured with DXA, and the structure of the radius and tibia were assessed with pQCT in 75 premenopausal obese (BMI > 30) women. The number of women in the ESR1 Pvu II genotype groups was 26 in TT, 37 in TC and 12 in CC. The CC genotype group had 7.8% (CI 3.3% to 12.6%) and 5.4% (CI 0.8% to 10.4%) narrower neck width than the TC and the TT groups, respectively. Cortical density at the tibial shaft among the CC genotype carriers was 1.5% (CI 0.0% to 3.0%) and 1.4% (CI 0.0% to 2.8%) higher than among the TC or TT carriers, respectively. Other bone traits did not show significant differences. Our results suggest that the less frequent CC genotype in obese premenopausal women is related to narrower femoral neck and higher cortical density at the tibial shaft compared to the TC and TT genotypes. Thus, this gene polymorphism seems to be associated specifically with bone structural traits rather than bone mass.