Effects of hormone replacement therapy on bone mineral density in Turkish patients with or without COL1A1 Sp1 binding...

To evaluate the effects of hormone replacement therapy (HRT) on bone mineral density (BMD) in patients with or without COL1A1 Sp1 binding site polymorphism.

Non-smoking otherwise healthy postmenopausal women (n=111), who had not received any kind of HRT for at least 3 years (between 2002 and 2005) at the onset of menopause, were included. All patients received 0.625 mg conjugated estrogen/2.5 mg medroxyprogesterone for 18 months. BMD by dual X-ray absorptiometry was measured at the lumbar spine and the femur neck initially and after 18th months of treatment. COL1A1 Sp1 binding site polymorphism was studied using the PCR-RFLP method.

After having the results of COL1A1 Sp1 binding site polymorphism, 79 (71.2%) patients were SS, 30(27.0%) were Ss and two (1.8%) were homozygous for ss. The mean age, weight and length of menopausal period were similar between the SS and Ss patients. The Ss heterozygotes had lower BMD values both at the lumbar spine and at the femur neck compared with the SS patients. This difference was also reflected in post treatment measurements. The increase in BMD scores was higher in the SS homozygotes than in the Ss patients.

Our preliminary data supports the fact that HRT had a lower increase in BMD scores following 18 months of treatment in COL1A1 s allele individuals compared with normal SS individuals. Therefore our study may provide evidence that the Sp1 polymorphism may ameliorate the effects of HRT on BMD, suggesting some additional regimens may be used to support bone strength and to decrease osteoporotic fractures.