Disparate genetic influences on polycystic ovary syndrome (PCOS) and type 2 diabetes revealed by a lack of association between common variants within the TCF7L2 gene and PCOS.

Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Old Road, Headington, Oxford OX3 7LJ, UK.
Diabetologia (Impact Factor: 6.88). 12/2007; 50(11):2318-22. DOI: 10.1007/s00125-007-0804-z
Source: PubMed

ABSTRACT Common variants of the gene encoding transcription factor 7-like 2 (TCF7L2) have a powerful effect on individual risk of type 2 diabetes (per allele odds ratio approximately 1.35). Polycystic ovary syndrome (PCOS) and type 2 diabetes are familial conditions sharing common features. Based on this, the aim of the present study was to establish whether variation in TCF7L2 also influences the development of PCOS.
We conducted a genetic association study of variants of TCF7L2 (rs7903146 and rs12255372) using both case-control and quantitative trait approaches. Case-control analyses were conducted in (1) 369 PCOS cases and 2574 controls of UK British/Irish origin, and (2) 540 women with PCOS symptoms and 1083 controls from the Northern Finland Birth Cohort of 1966. Quantitative trait analyses (androgen levels) were also performed (1249 individuals).
There was no association between rs7903146 and PCOS in the UK case-control study (Cochran-Armitage test, p = 0.51); nor with symptomatic status in the Finnish cohort (p = 0.36). In addition, there were no relationships between the TCF7L2 single nucleotide polymorphism rs7903146 and androgen levels (UK cases, p = 0.99; Finnish controls, p = 0.57; Finnish symptomatic cases, p = 0.80). Results at rs12255372 were similar, reflecting strong linkage disequilibrium with rs7903146.
Our study was powered to detect an effect on PCOS susceptibility similar to that previously reported for these variants on type 2 diabetes. Failure to detect any evident association with PCOS provides the strongest evidence yet that the genetic architecture of these related conditions is qualitatively distinct.

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    ABSTRACT: Abstract Objective: This meta-analysis was performed to evaluate the relationships between genetic polymorphisms in the TCF7L2 gene and polycystic ovary syndrome (PCOS) risk. Methods: The PubMed, Centralised Information Service for Complementary Medicine (CISCOM), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, Google Scholar, EBSCO, Cochrane Library, and Common Biorepository Model (CBM) databases were searched for relevant articles published before November 1st, 2013, without language restrictions. Meta-analysis was conducted using the STATA 12.0 software. The relationships were evaluated by calculating the pooled odds ratios (ORs) and their 95% confidence intervals (CIs). Seven case-control studies with a total 2458 PCOS patients and 5109 healthy subjects' met our inclusion criteria for qualitative data analysis. Two common polymorphisms (rs7903146 C→T and rs12255372 G→T) in the TCF7L2 gene were assessed. Results: The results of our meta-analysis suggested that TCF7L2 genetic polymorphisms might be strongly correlated with an increased risk of PCOS (allele model, OR=1.33, 95% CI=1.15-1.54, P<0.001; dominant model, OR=1.40, 95% CI=1.12-1.75, P=0.003), especially for the rs7903146 C→T polymorphism. A subgroup analysis was done to investigate the effect of ethnicity on an individual's risk of PCOS. Our results revealed positive significant correlations between TCF7L2 genetic polymorphisms and an increased risk of PCOS among Caucasians (allele model, OR=1.26, 95% CI=1.08-1.47, P=0.004; dominant model, OR=1.33, 95% CI=1.00-1.76, P=0.046) and Asians (allele model, OR=2.02, 95% CI=1.42-2.89, P<0.001; dominant model, OR=2.02, 95% CI=1.40-2.92, P<0.001), but not among Africans (all P<0.05). Conclusions: Our findings provide convincing evidence that TCF7L2 genetic polymorphisms may contribute to susceptibility to PCOS, especially for the rs7903146 C→T polymorphism among Caucasians and Asians.
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    ABSTRACT: To assess whether TCF7L2 single nucleotide polymorphisms rs7903146 C/T and rs11196236 C/T are associated with polycystic ovary syndrome (PCOS) in South Brazilian women. Cross-sectional study. 200 PCOS patients and 102 non-hirsute, ovulatory controls were genotyped by real-time polymerase-chain reaction. Haplotypes were constructed from the combination of both polymorphisms. Frequencies were inferred using the PHASE 2.1.1 software. The distribution of rs7903146 (PCOS, 54.4% CC; 28.5% CT; 17.1% TT; controls, 51.0% CC; 37.0% CT; 12.0% TT) and rs11196236 (PCOS, 4.3% CC; 33.5% CT; 62.2% TT; controls, 3.2% CC; 35.5% CT; 61.3% TT) was similar between the groups. rs7903146 and rs11196236 were not in linkage disequilibrium (|D´|=0.34; r2=0.07). PCOS participants were younger, with higher age-adjusted BMI, waist circumference, blood pressure, triglycerides, insulin, HOMA-IR and total testosterone, and lower HDL-c and SHBG vs. controls. In PCOS, no differences between genotypes and haplotypes were found for clinical and metabolic variables. However, for each T (rs7903146) and T (rs11196236) allele added to the haplotypes, a variation of 5.87 cm in waist (P trend=0.01), 10.7 mg/dL in total cholesterol (P trend=0.03), and 10.3 mg/dL in LDL-c (P trend=0.01) was recorded. TCF7L2 variants are probably not implicated in PCOS development in South Brazilian women.
    European Journal of Endocrinology 08/2013; · 3.69 Impact Factor
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    ABSTRACT: Background and Aims Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects women in their child-bearing age, and is often associated with insulin resistance and type 2 diabetes (T2DM). Given the overlap between PCOS and T2DM, we investigated the association of Transcription Factor 7-Like 2 (TCF7L2) variants rs4506565, rs7903146, rs12243326, and rs12255372 with the susceptibility to PCOS Subjects and Methods Study subjects comprised 119 Tunisian women with PCOS (mean age 29.8±4.7years), and 150 control women (mean age 30.6±5.9years). TCF7L2 genotyping was done by the allelic discrimination/real-time PCR method. Minor allele frequencies (MAF) of rs4506565 (P=0.61), rs7903146 (P=0.68), rs12243326 (P=0.56), and rs12255372 (P =0.60), were comparable between PCOS cases and controls subjects. As the four tested TCF7L2 variants were in linkage disequilibrium, 4-locus (rs4506565, rs7903146, rs12243326, rs12255372) haplotype analysis demonstrated that haplotype 2111 was initially negatively associated with PCOS [P=0.035; OR (95% CI)=0.13 (0.02 - 0.85)], which was later lost upon correcting for multiple comparisons [Pc=0.248]. Our data suggest that there is weak or no contribution of TCF7L2 gene polymorphism to PCOS in Tunisian women. Further studies with larger samples are necessary to confirm this observation.
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