The role of FTO variants in the susceptibility of polycystic ovary syndrome and in vitro fertilization outcomes in Chinese women.

We investigated the association between single nucleotide polymorphisms (SNPs) in the fat mass and obesity associated (FTO) gene (rs9926289 A/G, rs79206939 A/G, rs9930506 A/G, rs8050136 A/C, and rs1588413 C/T) and polycystic ovary syndrome (PCOS), as well as outcomes of in vitro fertilization (IVF). A case-control study consisting of 147 PCOS patients and 120 healthy controls was conducted. FTO SNPs were genotyped by PCR to determine allelic frequencies, and IVF outcomes were analyzed. The results showed that FTO rs8050136 (p = .025) and rs1588413 (p = .042) were significantly associated with PCOS susceptibility, and women with risk alleles were often found to be obese (p < .05). For SNP rs8050136, women with AA + AC genotypes had higher body mass indexes (BMIs), oral glucose tolerance test/2 h (OGTT) levels and implantation rates but lower follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG) day progesterone levels and ovulation numbers (all p < .05) than those with the CC genotype. For SNP rs1588413, women carrying risk alleles exhibited higher BMIs, implantation rate, and levels of luteinizing hormone (LH), estradiol, and OGTT/2 h (all p < .05) compared with those with non-risk genotypes. Therefore, these findings suggest that rs8050136 and rs1588413 are associated with PCOS susceptibility, and that women with risk alleles have less ovulation numbers but higher implantation rates than those with other genotypes.

Association between fat mass and obesity associated (FTO) gene rs9939609 A/T polymorphism and polycystic ovary syndrome: a systematic review and meta-analysis.

BACKGROUND: Up to now, numerous case-control studies have reported the associations between fat mass and obesity associated (FTO) gene rs9939609 A/T polymorphism and polycystic ovary syndrome (PCOS), however, without a consistent result. Hence we performed current systematic review and meta-analysis to clarify the controversial results. METHODS: Case-control studies reporting the relationship of rs9939609 A/T polymorphism and PCOS published before April 2015 were searched in Pubmed database without language restriction. Data was analyzed by Review Manager 5.2. RESULTS: A total of five studies involving 5010 PCOS patients and 5300 controls were included for further meta-analysis. The results of meta-analysis showed that the FTO gene rs9939609 A/T polymorphism was significantly different between PCOS group and control group in different gene models (For AA + AT vs. TT: OR = 1.41, 95% CI = 1.28-1.55, P < 0.00001. For AA vs. AT + TT: OR = 1.54, 95% CI = 1.25-1.89, P < 0.0001. For AA vs. TT: OR = 1.74, 95% CI = 1.38-2.18, P < 0.00001. For A vs. T: OR = 1.36, 95% CI = 1.25-1.47, P < 0.00001, respectively) suggesting that A allele was a risk factor for PCOS susceptibility. Furthermore, subgroup analysis in Asian and Caucasian ethnicities also found significant association between rs9939609 A/T polymorphism and PCOS (In Asian subgroup: OR = 1.43, 95% CI = 1.29-1.59, P < 0.0001. In Caucasian subgroup: OR = 1.33, 95% CI = 1.08-1.64, P = 0.008) CONCLUSION: This meta-analysis suggests that rs9939609 A/T polymorphism of FTO gene is associated with PCOS risk, and that A allele is a risk factor for PCOS susceptibility simultaneously.

New Insights into mTOR Signal Pathways in Ovarian-Related Diseases: Polycystic Ovary Syndrome and Ovarian Cancer

mTOR, the mammalian target of rapamycin, is a conserved serine/threonine kinase which belongs to the phosphatidyl-linositol kinase-related kinase (PIKK) family. It has two complexes called mTORC1 and mTORC2. It is well established that mTOR plays important roles in cell growth, proliferation and differentiation. Over-activation of the mTOR pathway is considered to have a relationship with the development of many types of diseases, including polycystic ovary syndrome (PCOS) and ovarian cancer (OC). mTOR pathway inhibitors, such as rapamycin and its derivatives, can directly or indirectly treat or relieve the symptoms of patients suffering from PCOS or OC. Moreover, mTOR inhibitors in combination with other chemical-molecular agents may have extraordinary efficacy. This paper will discuss links between mTOR signaling and PCOS and OC, and explore the mechanisms of mTOR inhibitors in treating these two diseases, with conclusions regarding the most effective therapeutic approaches.

The association between androgen receptor gene CAG polymorphism and polycystic ovary syndrome: a case-control study and meta-analysis.

PURPOSE: Many studies have been carried out to confirm the relationship between androgen receptor gene CAG repeat polymorphism and polycystic ovary syndrome (PCOS), without consistent results. Hence we conducted the current study to research this relationship. METHODS: 224 Chinese Han women with PCOS and 223 in vitro fertilization and embryo transplantation (IVF-ET) infertile women with tubal factor or male infertility served as the controls were recruited in our study. PCR-based assays were applied to genotype the (CAG)n repeat alleles. A meta-analysis including 1,536 PCOS patients and 1,807 controls was conducted to produce a pooled estimate. RESULTS: We observed that the CAG bi-allelic mean lengths were similar in PCOS patients and controls (22.65 ± 2.5 vs. 23.09 ± 2.1, P = 0.116). When CAG bi-allelic were divided into two categories (mean repeats ≤22, >22), the short AR-CAG bi-allelic showed more frequent in PCOS group than in controls (56.25% vs 29.14%, P < 0.001). Further analysis presented that, in PCOS, there was a lower mean CAG repeat lengths in mean bi-allelic lengths (22.3 ± 2.5 vs. 23.9 ± 2.2, P = 0.008) and long bi-allelic lengths (24.3 ± 1.4 vs. 25.9 ± 1.6, P = 0.05) among patients with testosterone less than 0.7 ng/ml compared with those whose testosterone was more than 0.7 ng/ml. Besides, the testosterone were positively correlated with the CAG polymorphism (r = 0.237, P = 0.008), which accorded with our meta-analysis results. CONCLUSIONS: The distribution of AR-CAG allele differed between PCOS patients and controls, and polymorphism of CAG repeat lengths may contribute to hyperandrogenism in PCOS.

[OATP 1B1 T521C/A388G is an important polymorphism gene related to neonatal hyperbilirubinemia].

OBJECTIVE: Multiple genetic and environmental factors contribute to the onset of many human diseases, such as neonatal hyperbilirubinemia. OATP 1B1 is an important polymorphism gene which transmembrane transports unconjugated bilirubin(UCB). Genetic polymorphisms that affect the functionality of the protein may potentially lead to altered transport characteristics. The T521C/A388G polymorphism of this gene has been reported to considerably reduce the transporting property of drugs like pravastatin, and may be involved in the membrane translocation of bilirubin. Some studies have shown that OATP 1B1 mediates bilirubin uptake from blood into the liver, and the OATP 1B1 polymorphism is a likely mechanism explaining the differences of bilirubin level in peripheral blood. The aim of this study was to evaluate the relationship between OATP 1B1 polymorphisms and neonatal hyperbilirubinemia. METHODS: A total of 220 newborn infants with hyperbilirubinemia were recruited from Hunan Children Hospital from November 2008 to December 2009 according to the diagnostic criteria. Age and sex matched control subjects comprised of 200 unrelated, hyperbilirubinemia-free newborns. Biochemical and clinical data were collected from the case history. One ml venous blood samples in EDTA vials were taken from each subject and DNA was isolated from peripheral leukocytes by standard methods, preserved in 4°C. 1 - 2 ml venous blood samples were also taken for detecting the serum total bilirubin and direct bilirubin level by chemical oxidation method. OATP 1B1 T521C/A388G polymorphisms were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Allele and genotype frequencies were compared between patients and control. The gene polymorphism and risk of disease were also analyzed. Serum total bilirubin, conjugated bilirubin and unconjugated bilirubin levels were compared between different OATP 1B1 T521C/A388G genotypes. RESULTS: Allele frequencies in patients and control population were in Hardy-Weinberg equilibrium (P > 0.05). Allele and genotype frequencies of the OATP 1B1 T521C polymorphism in patients were significantly different from the controls. The OATP 1B1 521C allele frequency was only 8.2% in patients, while reached 14.0% in the control group which was very close to the frequency of common Chinese people. However, the proportion of wild type genotypes was significantly higher than those of the controls, reached 84.1%. The 521 C allele and genotypes carrying 521 C allele illustrated low risk for neonatal hyperbilirubinemia (OR = 0.530, 95%CI = 0.328 - 0.857; OR = 0.541, 95%CI = 0.344 - 0.851). However, the frequencies of alleles and genotypes of SLCO1B1 A388G did not differ significantly from those of the controls, and this polymorphism did not influence susceptibility to such disease. Among the three OATP 1B1 A388G genotypes, the level of total serum bilirubin (TSB), direct bilirubin (DB) and unconjugated bilirubin (UCB) were significantly different. Values of TSB, DB and UCB were the highest in wild type subjects, lower in heterozygotes, and the lowest in mutant homozygotes. TSB and UCB in patients with wild type genotypes reached 602.5 µmol/L and 585.0 µmol/L respectively, nearly twice the average value of homozygous patients. While the TSB and UCB in homozygotes were below the average value of all patients, only 351.7 µmol/L and 338.8 µmol/L respectively. CONCLUSIONS: Our findings indicated that OATP 1B1 A388G polymorphism has a notable influence on the serum bilirubin level in neonatal hyperbilirubinemia patients. The OATP 1B1 521T allele may be a potential risk factor of such disease. OATP 1B1 T521C/A388G was an important polymorphism gene which related with neonatal hyperbilirubinemia. Future study should involve other polymorphisms of OATP 1B1, more candidate genes and environmental risk factors. It is also necessary to investigate their association with the severity and prognosis of this disease in order to elucidate the genetic pathogenesis of neonatal hyperbilirubinemia as a complex disease. This study should be repeated in a larger population and different ethnic groups.

[Novel mechanism of 3' exonuclease of polymerase in maintenance of DNA replication fidelity and its application in SNP assay].

Polymerase with 3' to 5'exonulcease plays an important role in the maintenance of in vivo DNA replication fidelity. In order to develop more reliable SNP assays, we revisit the underlying molecular mechanisms by which DNA polymerases with 3' exonucleases maintain high fidelity of DNA replication. In addition to mismatch removal by proofreading, we recently discovered a premature termination of polymerization by a new mechanism of OFF-switch. This novel ON/OFF switch turns off DNA polymerization from mismatched primers and turns on DNA polymerization from matched primers. Two SNP assays were developed based on the proofreading and the newly identified OFF-switch respectively: terminal labeled primer extension and the ON/OFF switch operated SNP assay. These two new methods are well adapted to conventional techniques such as electrophoresis, real time PCR, microplates, and microarray. Application of these reliable SNP assays will greatly facilitate genetic and biomedical studies in the post-genome era.

Exo+ proofreading polymerases mediate genetic analysis and its application in biomedical studies.

Polymerases with a proofreading function in their internal 3' to 5' exonuclease possess high fidelity for DNA replication both in vivo and in vitro. The obstacle facing Exo+ polymerases for single nucleotide polymorphism (SNP) detection could be bypassed by using primer-3'-termini modification. This hypothesis has been well tested using three types of modified allele specific primers with: 3' labeling, 3' to 5' exonuclease resistance, and 3' dehydroxylation. Accordingly, three new SNP assaying methods have been developed to carry out genome-wide genotyping, taking advantage of the enzymatic properties of Exo+ polymerases. These new mutation detection assays are widely adaptable to a variety of platforms, including multi-well plate and microarray technologies. Application of Exo+ polymerases to genetic analysis, including genotyping that is mostly relevant to pharma-cogenetics, high-fidelity gene expression profiling, rare mutation detection and mutation load assay, will help to accelerate the pace of personalized medicine. In this review paper, we will first introduce three new assays that we have recently developed, and then describe a number of their applications in pharmacogenetics and in other biomedical studies.

On/off switch mediated by Exo+ polymerases: experimental analysis for its physiological and technological implications.

The potential physiological role and technological application of the premature termination of DNA polymerization through the off-switch of exo+ polymerases were studied using 3' phosphorothioate-modified or unmodified primers with single base mismatch distal to the 3' terminus. With exonuclease-digestible unmodified primers, a gradient premature termination of DNA polymerization was observed when amplified with exo+ polymerases. With 3' allele specific phosphorothioate-modified primers, an efficient off-switch effect occurred in the discrimination of a single nucleotide polymorphism when directly using genomic DNA. Clearly, the off-switch of exo+ polymerases is useful in biomedical research.

[Effect of 3' exonuclease activity of polymerase on extension of phosphorothioate-modified primers].

OBJECTIVE: To determine whether 3'phosphorothioate-modified-2 terminal mismatched primers can turn off DNA polymerization mediated by Exo(+) polymerase. METHODS: Two-directional primer extension was performed using polymerase with and without 3' exonuclease activity. The effects of unmodified primers and 3' phosphorothioate-modified primers on primer extension were evaluated. RESULTS: Exo(-) polymerase yielded products from matched and mismatched primers regardless of their modification. However, 3' phosphorothioate-modified primers with a single base mismatch at -2 position worked similarly to the terminal (-1) mismatched primers in triggering the novelly reported "off-switch" of Exo(+) polymerase. CONCLUSION: These data suggested that the "off-switch" can be of enormous application in the diagnosis of single gene diseases and in the association studies by single nucleotide polymorphism screening.