Effect of estrogen receptor-α gene polymorphism on serum osteoprotegerin and calcaneus bone density in postmenopausal women in Guangxi Zhuang nationality

Abstract

Objective To investigate the effect of estrogen receptor-α gene polymorphism on osteoprotegerin(OPG)and calcaneus bone density in early and late postmenopausal women in Guangxi Zhuang nationality, in order to provide the theoretical basis for the early prevention and treatment of postmenopausal osteoporosis caused by estrogen receptor gene-induced osteoprotegerin reduction. Methods The broadband ultrasound attenuation in the right heel bone was measured by quantitative ultrasound bone densitometry in 621 postmenopausal women of Guangxi Zhuang nationality.Peripheral blood mononuclear cells and their DNA were extracted.Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP)was used to detect the estrogen receptor-α gene polymorphism.Serum osteoprotegerin level was determined by enzyme-linked immunosorbent assay.The differences of data distribution of OPG and calcaneus bone density were compared between five items of 3 genotypes and 2 alleles at the same age group of 40-, 45-, 50-, 55-, 60-, 65-, 70-, 75-80 years. Results Women aged 60 years and over versus those aged 40-59 years showed that serum osteoprotegerin(OPG)and bone mineral density(BMD)were decreased(P 0.05). Women aged 60 years and over showed that ER-α Puv Ⅱ polymorphism of allele big P versus p, Pp, pp, PP in the same age groups had significantly decreased serum osteoprotegerin and bone mineral density.Women aged 65 years and over showed that ER-α XbaⅠpolymorphism of heterozygote Xx versus xx, XX, X, x in the same age groups had a significantly increased serum osteoprotegerin and bone mineral density(P<0.05). Conclusions Women with big P allele of ER-α PvuⅡpolymorphism have low serum osteoprotegerin level and a decreased bone mineral density, who are prone to postmenopausal osteoporosis.Thus, P allele of ER-α PvuⅡpolymorphism is a causative agent.More attention should be paid to early prevention and treatment.But, women with the Xx heterozygote of ER-α XbaⅠpolymorphism have high serum osteoprotegerin level and an increased bone mineral density, who are not easy to suffer from postmenopausal osteoporosis.Therefore, Xx heterozygote of ER-α XbaⅠpolymorphism is a protective agent.The prevention and treatment of postmenopausal osteoporosis should be individualized based on estrogen receptor-α gene polymorphism. Key words: Zhuang nationality; Receptors, estrogen; Polymorphism, single nucleotide; Osteoprotegerin