Vitamin D receptor 1a promotor -1521 G/C and -1012 A/G polymorphisms in polycystic ovary syndrome.

OBJECTIVE: The aim of this case-control study was to investigate whether the vitamin D receptor (VDR) 1a promoter gene polymorphisms are associated with susceptibility to polycystic ovary syndrome (PCOS).
METHODS: Women with PCOS and a control group, all aged 18-45 years, were enrolled. Genotypes of two functional single nucleotide polymorphisms (SNPs), the 1521 bp (G/C) and 1012 bp (A/G), located on the 1a promoter of the VDR gene were determined by using direct sequencing. Serum 25-hydroxyvitamin D levels were measured by ELISA.
RESULTS: Two functional SNPs in the 1a promoter region of the VDR gene were in complete linkage disequilibrium. The genotype distributions of these two polymorphisms in the PCOS group were not significantly different from those of the control group. Further subgroup analyses according to body mass index also revealed no significant differences in the genotype distribution in the PCOS group. Significantly lower serum 25-hydroxyvitamin D levels were observed in the heterozygous 1521CG/1012GA haplotype of both groups. Metformin treatment was only effective to increase serum 25-hydroxyvitamin D levels in PCOS patients carrying the homozygous 1521G/1012A haplotype.
CONCLUSION: These results suggest that the VDR 1a promoter polymorphisms may not be associated with the risk for PCOS, but are associated with serum 25-hydroxyvitamin D levels. Metformin treatment will be beneficial to PCOS patients without the VDR 1a promoter variant in Taiwanese population.