Association of VDBP and CYP2R1 gene polymorphisms with vitamin D status in women with polycystic ovarian syndrome: a north Indian study

Polycystic ovarian syndrome (PCOS) is the most common endocrine abnormality among women of reproductive age and is usually associated with oligo-ovulation/anovulation, obesity, and insulin resistance. Hypovitaminosis D may also be a primary factor in the initiation and development of PCOS. However, little is known about the role of genetic variation in vitamin D metabolism in PCOS aetiology. Therefore, we studied the genetic polymorphisms of CYP2R1 and vitamin D binding protein (VDBP) in an Indian population. Serum vitamin D was measured by ELISA. Genotyping of VDBP single nucleotide polymorphisms (SNPs) rs7041 (HaeIII; G > T) and rs4588 (StyI; A > C) and CYP2R1 SNP rs2060793 (HinfI; A > G) was carried out by restriction fragment length polymorphism in 50 cases of PCOS that were compared with 50 age-matched healthy women. Vitamin D levels were found to be significantly lower in women with PCOS (p = 0.008) than in age-matched controls. There was no significant difference in genotype frequencies of all three polymorphisms (rs7041, rs4588, and rs2060793) between PCOS and control women. In women with a vitamin D deficiency (< 20 ng/ml), the GT allele of the VDBP SNP rs7041 (p value =0.04), the VDBP allelic combination Gc1F/1F (T allele of rs4588 and C allele of rs7041) (p value =0.03), and the GA allele of the CYP2R1 SNP rs2060793 (p = 0.05) were associated with an increased risk of developing PCOS. The present study shows that the GT allele of VDBP SNP rs7041, the VDBP allelic combination (GC1F/1F), and GA allele of CYP2R1 SNP rs2060793 in vitamin D deficient women increase the risk of PCOS.