The Relationship between Polymorphisms in the Vitamin D Receptor Gene and Bone Mineral Density in Postmenopausal Women

The objective of this study was to identify, through a systematic review of the literature, Vitamin D receptor gene (VDR) polymorphisms related to osteoporosis and their effects on bone mineral density (BMD). The articles dated between January 2000 and December 2011 in the Scielo and PubMed databases were reviewed. A total of 23 articles that studied the association between the BsmI, ApaI, FokI, and TaqI polymorphisms and bone mineral density in postmenopausal women were selected. We found systematic studies/meta-analysis (level E-I) and case-control/cohort (level E-IV) studies. No definite conclusions can be made regarding the association of BsmI, ApaI, FokI, and TaqI polymorphisms with BMD among postmenopausal women. Larger and more rigorous analytical studies with consideration of gene-gene/environment interactions are needed to further dissect the mechanisms by which VDR alleles influence BMD. 1. Introduction Osteoporosis is a systemic skeletal disease characterised by low bone mineral density (BMD) and the deterioration of the bone microarchitecture that leads to increased bone frailty and high-risk fractures [1]. It is the most common metabolic bone disease in the world, affecting one in three women and one in eight men over 50 years of age [2]. Postmenopausal osteoporosis is a major health problem due to its high prevalence and the large social health costs it incurs because of its clinical manifestations, specifically fractures. Approximately 200 million people worldwide suffer from this disease. The treatment of this disease has a direct annual cost of 54 billion dollars in Europe, the United States, and Canada alone, not including the additional ten million dollars in indirect costs. In Europe, the direct cost of this disease reached 48 billion Euros in the year 2000; the costs incurred solely in the hospitals have increased by 33% over the last three years. In Spain, osteoporosis is the most prevalent metabolic bone disease. Studies in twins [3, 4] and relatives [5, 6] estimate that genetic factors account for up to 50–90% of the total factors that determine bone mass [7–9] and contribute significantly to the following processes: peak bone mass acquisition [4, 5, 10], turnover [11, 12], and loss of bone mass throughout the lifetime of the patient [13]. Four polymorphisms (BsmI, TaqI, ApaI, and FokI) in the Vitamin D receptor (VDR) gene have been studied more frequently because of their associations with BMD and osteoporosis. The VDR gene is located on the long arm of chromosome 12 (12q12.11) and is a member of the genetic receptor