Genetic variant in the aquaporin 9 gene is associated with bone mineral density in postmenopausal women

This study investigated whether single nucleotide polymorphisms (SNP) in the aquaporin 9 (AQP9) gene is associated with bone mineral density (BMD) in Thai postmenopausal women, after an initial genome-wide screening using high-throughput SNP genotyping in pooled DNA samples. Subjects consisted of 516 postmenopausal women aged 50 or more. High-throughput SNP screening was performed by comparing the estimated allele frequency derived from hybridization signal intensities of pooled DNA samples on the Affymetrix 500 K SNP genotyping chip set. The SNP was then genotyped for each subject individually. Data were expressed as mean +/- A SEM. Pooled DNA SNP screening revealed the allele frequency of an intronic A/T SNP rs2414539 in the AQP9 gene as being different between subjects with femoral neck BMD in tertiles 1 and 3. Individual genotyping in all subjects revealed that femoral neck BMD in subjects with TT, TA, and AA genotypes were 0.79 +/- A 0.06 (n = 3), 0.75 +/- A 0.01 (n = 98), and 0.71 +/- A 0.01 g/cm(2) (n = 415), respectively. The presence of the T allele in rs2414539 was associated with femoral neck BMD (r = 0.11, P < 0.05) but not with lumbar spine BMD. The relationship was still significant after controlling for body weight and age (P < 0.05). Genetic variation in the AQP9 gene is associated with femoral neck BMD in postmenopausal women, and may represent one of the susceptibility genes for phenotypes related to bone mass.