Relationship of Volumetric Bone Mineral Density and Structural Parameters with ERα Gene Polymorphisms

Abstract

Bone mineral density (BMD) contributes to bone strength, and methods for clinical assessment of bone quality characteristics beyond what can be gathered by BMD are awaited. Peripheral quantitative computed tomography (pQCT) allows for separate assessments of cortical and trabecular bone, providing information on bone geometry. Previous studies examining the relationship between estrogen receptor α (ERα) gene polymorphisms and BMD have been performed in large populations. However, only limited information is available on the possible segregation of ERα gene polymorphisms with bone structural properties. The aim of our study was to evaluate the association of XbaI and PvuII ERα gene polymorphisms with QCT parameters. We studied 900 subjects (541 women, 449 men) participating to the InCHIANTI study. By tibial pQCT we evaluated trabecular volumetric BMD, cortical volumetric BMD, cortical bone area, and cortical thickness (CtTh). Subjects were genotyped for ERα gene PvuII and XbaI polymorphisms. Analysis of variance was used for statistical analysis. Male subjects with PP and XX genotypes had higher geometric parameters, and female subjects with XX and PP genotypes showed higher densitometric parameters than other genotypes; however, the differences did not reach statistical significance. After adjustment for potential confounders, we found a significant (P = 0.002) CtTh difference across PvuII polymorphism in male subjects, with higher CtTh values in PP genotypes with respect to Pp and pp genotypes. These results show a relationship between the presence of the P allele and higher values of CtTh in male subjects, indicating for ERα a role in the control of tibial bone geometry. KeywordsCortical thickness; ERα gene polymorphism; Peripheral bone; Quantitative computed tomography; Volumetric bone mineral density Osteoporosis is a common skeletal disorder characterized by compromised bone strength predisposing the affected individuals to an increased susceptibility to fragility fracture [1]. Bone strength is the result of both bone mineral density (BMD) and bone quality, the latter encompassing a number of factors, such as bone turnover, mineralization, microarchitecture, Correspondence to: M. L. Brandi; E-mail: mbrandi@dmi.unifi.it. The aim of our study was to evaluate the influence of XbaI and PvuII ERα gene polymorphisms on volumetric BMD (vBMD) and on structural parameters assessed using tibial quantitative computed tomography (QCT) in a large and homogeneous population-based sample of Caucasian men and women. NIH Public Access Subjects and Methods The Population SampleInCHIANTI is an epidemiological study performed in two Italian towns located in the Chianti countryside: Greve (11,709 inhabitants, rural area) and Bagno a Ripoli (village of Antella, 4,704 inhabitants, just outside the urban area of Florence). The study population consisted of a random sample of the population aged 65 years and older living in the two catchment areas and 30 men and 30 women randomly selected in each decade between 20 and 70 ye...

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