Polymorphisms in the vitamin D receptor gene and the androgen receptor gene and the risk of benign prostatic hyperplasia

Objective: Little is known about risk factors for the development of benign prostatic hyperplasia (BPH). Recently, associations were observed between prostate cancer (CaP) risk and polymorphisms in the vitamin D receptor (VDR ) gene and the androgen receptor (AR) gene. Since both receptors are releva nt for prostate growth, the VDR and AR are also expected to be involved in the development of BPH. The objective of th is study is to establish the re lationship between the risk of BPH and a polymorphism in the number of CAG repeats in the AR gene and a TaqI restriction enzyme polymorphism in the VD R gene. Methods: For this study, 98 patients who had been treated for BPH-related c omplaints and 61 convenience controls (predominantly bladder cancer patient s) were recruited from the outpatient clinic. DNA was isolated from periphe ral blood, and genotyping was performed with PCR-based methods. Means as we ll as odds ratios (ORs) with 95% confidence intervals (CI) were calculated using SPSS software. Results: The mean number of CAG repeats in the AR gene in patients and cont rols was found to be similar: 21.8 (SD = 2.8) and 21.9 (SD = 2.9), respecti vely. In the subgroup of patients with a prostate volume of at least 50 cm( 3), the mean number of repeats was 21.5 (SD = 2.6). The OR for BPH for indi viduals with homozygous presence of the VDR TaqI restriction fragment lengt h polymorphism (RFLP) (tt) versus individuals with homozygous absence (TT) or heterozygotes (Tt) was found to be 1.0 (95% CI 0.4-2.4). For individuals with a prostate volume of at least 50 cm(3), the OR was 1.2 (95% CI 0.5-3. 2). Conclusion: Unlike earlier observations in prostate cancer, we did not find an association between the CAG repeat polymorphism in the AR gene and the TaqI RFLP polymorphism in the VDR gene and the risk of BPH. Copyright (C) 2 000 S. Karger AG, Basel.