Association of type 2 diabetes mellitus genes in polycystic ovary syndrome aetiology among women from southern India.

BACKGROUND & OBJECTIVES: Polycystic ovary syndrome (PCOS) is the most common reproductive endocrine disorder of premenopausal women. Given the phenotypic overlap between PCOS and type 2 diabetes mellitus (T2DM), this study was carried out to investigate whether genes implicated in T2DM were also involved in the susceptibility to PCOS among women from southern India. METHODS: A total of 248 women with PCOS and 210 healthy women as controls were genotyped for a panel of 15 single nucleotide polymorphisms (SNPs) from the nine T2DM genes, such as TCF7L2, IGF2BP2, SLC30A8, HHEX, CDKAL1, CDKN2A, IRS1, CAPN10 and PPARG, on Sequenom MassARRAY platform. RESULTS: None of the 15 SNPs were found to be significantly associated with PCOS after Bonferroni correction for multiple testing, either in the univariate or multivariate context. The cumulative effect of risk alleles observed with reference to T2DM was also not seen with reference to PCOS. INTERPRETATION & CONCLUSIONS: The nine T2DM genes considered in this exploratory study might not be the primary susceptibility factors for PCOS among Indian women. Our results supplement the lack of evidence of the association of T2DM genes with PCOS among the Chinese and Caucasians hinting at the possible universality of this pattern. Specifically designed comprehensive studies that include women with T2DM and PCOS are required to explore the precise role of the diabetes genes.

Association of vitamin D receptor gene polymorphisms with polycystic ovary syndrome among Indian women.

BACKGROUND & OBJECTIVES: The Vitamin-D receptor (VDR) regulates vitamin D levels and calcium metabolism in the body and these are known to be associated with endocrine dysfunctions, insulin resistance and type-2 diabetes in polycystic ovarian syndrome (PCOS). Studies on VDR polymorphisms among PCOS women are sparse. We undertook this study to investigate the association pattern of VDR polymorphisms (Cdx2, Fok1, Apa1 and Taq1) with PCOS among Indian women. METHODS: For the present study, 250 women with PCOS and 250 normal healthy control women were selected from Hyderabad city, Telangana, India. The four VDR polymorphisms were genotyped and analysed using ASM-PCR (allele specific multiple PCR) and PCR-RFLP (restriction fragment length polymorphism). RESULTS: The genotype and allele frequency distributions of only Cdx2 showed significant difference between the PCOS cases and control women, indicating protective role of this SNP against PCOS phenotype. However, significant association was observed between VDR genotypes and some of the PCOS specific clinical/biochemical traits. For example, Fok1 showed a significant genotypic difference for the presence of infertility and Cdx2 genotpes showed association with testosterone levels. Further, the two haplotypes, ACCA and ACTA, were found to be significantly associated with PCOS indicating haplotype specific risk. INTERPRETATION & CONCLUSIONS: Although VDR polymorphisms have not shown significant association with PCOS, in view of functional significance of the SNPs considered, one cannot yet rule out the possibility of their association with PCOS. Further, specifically designed studies on large cohorts are required to conclusively establish the role of VDR polymorphisms in PCOS, particularly including data on vitamin D levels.

The role of epistasis in the etiology of Polycystic Ovary Syndrome among Indian women: SNP-SNP and SNP-environment interactions.

Polycystic Ovary Syndrome (PCOS) is the most common endocrinopathy in women of reproductive age. It is a heterogeneous androgen excess disorder determined by the interaction of multiple genetic and environmental factors. Our earlier analysis on a panel of six candidate genes (Androgen receptor CAG repeats, Follistatin, Luteinizing hormone ß subunit, Calpain10, Insulin receptor substrate-1 and PPARγ) based on 250 PCOS cases and 299 controls revealed significant association patterns with PCOS among South-Indian women. We report here for the first time, the SNP-SNP and SNP-environment interactions of these genes in the same cohort. Both multivariate logistic regression as well as epistasis analysis (using Multifactor dimensionality reduction software) yielded significant results (P < 0.05). All CAPN10 SNPs show association (either risk-conferring or protective) in the obese group, highlighting the importance of this gene in the PCOS pathophysiology. LHP7(LHß) and UCSNP44(CAPN10) emerged to be the prominent SNPs in the SNP-SNP interaction analysis. The best SNP-SNP interaction model was obtained between CAPN10 UCSNP-44 and PPARγ His447His, implying a significant metabolic component in the PCOS pathology. Replicating our findings in BMI-specific cohorts in different ethnic populations would be warranted in future to identify the physiological networks in PCOS.

Association of CAPN10 SNPs and haplotypes with polycystic ovary syndrome among South Indian Women.

Polycystic Ovary Syndrome (PCOS) is known to be characterized by metabolic disorder in which hyperinsulinemia and peripheral insulin resistance are central features. Given the physiological overlap between PCOS and type-2 diabetes (T2DM), and calpain 10 gene (CAPN10) being a strong candidate for T2DM, a number of studies have analyzed CAPN10 SNPs among PCOS women yielding contradictory results. Our study is first of its kind to investigate the association pattern of CAPN10 polymorphisms (UCSNP-44, 43, 56, 19 and 63) with PCOS among Indian women. 250 PCOS cases and 299 controls from Southern India were recruited for this study. Allele and genotype frequencies of the SNPs were determined and compared between the cases and controls. Results show significant association of UCSNP-44 genotype CC with PCOS (p = 0.007) with highly significant odds ratio when compared to TC (OR = 2.51, p = 0.003, 95% CI = 1.37-4.61) as well as TT (OR = 1.94, p = 0.016, 95% CI = 1.13-3.34). While the haplotype carrying the SNP-44 and SNP-19 variants (21121) exhibited a 2 fold increase in the risk for PCOS (OR = 2.37, p = 0.03), the haplotype containing SNP-56 and SNP-19 variants (11221) seems to have a protective role against PCOS (OR = 0.20, p = 0.004). Our results support the earlier evidence for a possible role of UCSNP-44 of the CAPN10 gene in the manifestation of PCOS.

Polymorphisms in the IRS-1 and PPAR-γ genes and their association with polycystic ovary syndrome among South Indian women.

Polycystic ovary syndrome is known to be characterized by metabolic abnormalities such as hyperinsulinemia, adiposity and dyslipidemia. Both insulin receptor substrate-1 and peroxisome proliferator-activated receptor-γ have emerged as significant candidate genes in the pathogenesis of PCOS. In this study, we report for the first time, the association pattern of these genes with PCOS among South Indian women. Two hundred fifty PCOS cases and 299 controls were sequenced for IRS-1 exon1 and PPAR-γ exon 2 and exon 6 to study the already reported SNPs in other ethnic groups and to identify any novel SNP in these exonic regions specific to the Indian population. We did not find any novel SNP in our population except for those already reported- two IRS-1 polymorphisms (Gly972Arg and G2323A) and two PPAR-γ polymorphisms (Pro12Ala and His447His). While the IRS-1 polymorphic alleles had a similar distribution between cases and controls, the PPAR-γ exon 2 Ala allele and exon 6 His447His T allele were significantly more in the controls than in the cases (p≤0.05). Haplotype association analysis also suggests that both IRS-1 and PPAR-γ haplotypes with mutations depicted reduced frequency of hyperandrogenic and metabolic traits in PCOS compared to the haplotype with only wild type alleles. Our study on Indian women suggests that while IRS-1, contrary to the earlier findings in other ethnic groups, seems to have a probable protective role against development of specific PCOS sub-phenotypes, the evidence for a probable protective role of PPAR-γ is reaffirmed in our study.

Role of luteinizing hormone ß-subunit gene variants among South Indian women with polycystic ovary syndrome.

Abnormal luteinizing hormone (LH) secretion and action are known to affect ovarian steroidogenesis and thus playing a crucial role in manifestation of polycystic ovary syndrome (PCOS). This study is first of its kind to study association of LH ß-subunit gene variants with PCOS among South-Indian women. 250 PCOS cases and 299 controls were recruited for the study. All the exons of LH ß gene were screened. Allele and genotype frequencies of the SNPs were compared between the cases and controls. We identified seven SNPs in the LH ß gene; one SNP in exon 3 (rs#1056917) exhibited significant difference in the allele frequency between the PCOS cases and controls (p=0.015). Although, the LH ß variants that are found to be more frequent among PCOS cases are silent in nature and not of any functional significance, they might influence other significant functional polymorphisms in the hypothalamic-pituitary-gonadal axis which needs to be explored.

Role of androgen receptor CAG repeat polymorphism and X-inactivation in the manifestation of recurrent spontaneous abortions in Indian women.

The aim of the present study was to investigate the role of CAG repeat polymorphism and X-chromosome Inactivation (XCI) pattern in Recurrent Spontaneous Abortions among Indian women which has not been hitherto explored. 117 RSA cases and 224 Controls were included in the study. Cases were recruited from two different hospitals--Lakshmi Fertility Clinic, Nellore and Fernandez Maternity Hospital, Hyderabad. Controls were roughly matched for age, ethnicity and socioeconomic status. The CAG repeats of the Androgen Receptor gene were genotyped using a PCR-based assay and were analysed using the GeneMapper software to determine the CAG repeat length. XCI analysis was also carried out to assess the inactivation percentages. RSA cases had a significantly greater frequency of allele sizes in the polymorphic range above 19 repeats (p = 0.006), which is the median value of the controls, and in the biallelic mean range above 21 repeats (p = 0.002). We found no evidence of abnormal incidence of skewed X-inactivation. We conclude that longer CAG repeat lengths are associated with increased odds for RSA with statistical power estimated to be ∼90%.

Androgen receptor CAG repeat polymorphism and epigenetic influence among the south Indian women with Polycystic Ovary Syndrome.

The present study was carried out to assess the role of androgen receptor CAG repeat polymorphism and X chromosome inactivation (XCI) pattern among Indian PCOS women and controls which has not been hitherto explored and also to test the hypothesis that shorter CAG alleles would be preferentially activated in PCOS. CAG repeat polymorphism and X chromosome methylation patterns were compared between PCOS and non-PCOS women. 250 PCOS women and 299 controls were included for this study. Androgen receptor CAG repeat sizes, XCI percentages, and clinical and biochemical parameters were measured. The mean CAG repeat number is similar between the cases (18.74±0.13) and controls (18.73±0.12). The obese PCOS women were significantly more frequent in the <18 and >20 CAG repeat category than the lean PCOS women, yielding a highly significant odds (p=0.001). Among the women with non-random X-inactivation, alleles with <19 repeats were more frequently activated among cases than controls (p=0.33). CAG repeat polymorphism by itself cannot be considered as a useful marker for discriminating PCOS. We observed a trend of preferential activation of the shorter allele among the PCOS cases with non random XCI pattern. In the obese PCOS women, this microsatellite variation may account for the hyperandrogenicity to a larger extent than the lean PCOS women.