Family-based And Case-control Analysis Of INSR Gene Polymorphisms In Chinese PCOS

Part ⅠCase-control based study between polymorphisms in the INSR gene and polycystic ovary syndromeBackground:Polycystic ovary syndrome (PCOS) is the most common reproductive endocrinopathy occurring in5-8%of female population of reproductive age. It is a highly complicated and heterogeneous endocrinopathy which is characterized by chronic anovulation and high androgen hematic disease.Up to now, the inheritance mode of PCOS and the molecular mechanisms underlying PCOS aetiology still shrouded in mystery. In recent years, most scholars believe that it’s pathophysiological mechanism is insulin resistance (IR) and metabolic disorders caused by secondary hyperinsulinemia (HI), which may bring serious long-term complications to PCOS women. It mainly includes insulin resistance (IR), type2diabetes mellitus (T2DM), hyperlipidemia, cardiovascular disease (CVD) and even the metabolic syndrome (MS) caused by the glucolipid metabolic abnormalities, and the increased risk of estrogen dependent tumor caused by chronic anovulatory. A great number of candidate genes have been identified as susceptibility genes of PCOS. Insulin receptor (INSR) which is an indispensable component of insulin signaling pathway could be a plausible candidate gene of PCOS. The INSR gene is located on chromosome19p13.3, which plays an important role in insulin metabolism. The tyrosine kinase domain mutations of the insulin receptor have been shown to cause severe hyperinsulinemia and IR. Studies have found that single nucleotide polymorphism (SNP) rs2252673was associated with PCOS in Koreans and Caucasians. This Case-control based study was designed to determine whether an association exists between SNP rs2252673of INSR gene and PCOS in Han Chinese.Objective:This study was designed to determine whether an association exists between single nucleotide polymorphism (SNP) variant rs2252673of INSR gene and PCOS in Han Chinese in order to identify INSR as a genetic susceptibility factor for PCOS.Methods:A total of224women with PCOS and192controls were recruited from the Center for Reproductive Medicine, Shandong University, from July2007to April2013. Serum levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T), prolactin (PRL), estrodiol (E2) were measured. Serum levels of fasting blood glucose (FBG) and fasting insulin (FINS), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL) and high-density lipoprotein cholesterol (HDL) were measured after12hour empty-stomach. Height and weight were measured while BMI were calculated. Genomic DNA was extracted according to the manufacturer’s protocol. SNP rs2252673of INSR was amplified by polymerase chain reaction (PCR) and then sequenced on an automated sequencer. Moreover, we compare it’s clinical and metabolic features of the patients with PCOS according to the genotypes. The subjects were divided into different groups according to BMI, and then the results were compared between the different groups.Results:(1) The genotype frequencies in the PCOS group and the control group of rs2252673—CC,CG,GG were8%,38.8%,53.1%and14.6%,42.2%,43.2%respectively. The allele frequencies in the PCOS group and the control group of C and G were27.5%,72.5%and35.7%,64.3%respectively.There were statistical differences in genotype frequencies and allele frequencies between two groups(all P<0.05).(2) No significant differences were observed in the different genotype according to clinical and metabolic characteristics of women with PCOS. But when merging the genotype CG and GG, we surprised to see carriers of the CG and GG genotypes in women with PCOS were slightly associated with total cholesterol (TC) levels (t=2.072, p=0.048) and lower high-density lipoprotein (HDL)levels(t=2.274,p=0.026). Although statistical significance was not achieved, there was an increased tendency in fasting blood glucose (FBG) and fasting insulin (FINS) levels in CG and GG genotypes in PCOS cases.(3) Between the obesity and the non-obesity with PCOS, there was no statistical significance in the genotype and allele frequencies (χ2=0.054, p=0.974; χ2=0.022, p=0.883).Conclusion:G allele frequency of rs2252673in PCOS group was obviously higher than that of control group, which hint that the carrier of G allele may have higher risk of PCOS. The study showed that INSR gene was associated with glucolipid metabolic disorders of PCOS, the SNP rs2252673was associated with PCOS and this association was not affected by weight, which further prompt that INSR gene appears to be a susceptibility gene for PCOS. Part ⅡFamily-based analysis of INSR gene polymorphisms in Chinese polycystic ovary syndromeBackground:Polycystic ovary syndrome (PCOS) has strong familial clustering. First-degree relatives of women with PCOS exhibit an increased prevalence of IR, whether or not they suffer from PCOS. Moreover, insulin receptor (INSR) plays an important role in insulin metabolism.This study was designed to determine whether an association exists between three single nucleotide polymorphism (SNP) variants (rs3786681, rsl7253937and rs2252673) of INSR gene and PCOS in Han Chinese. A total of224family trios (672participants in total) were enrolled in this family-based transmission disequilibrium test (TDT). The TDT analysis method is not influenced by genetic method, and population stratification, environmental factors or genetic heterogeneity. Studies have found that single nucleotide polymorphism (SNP) rs2252673was associated with PCOS in Koreans and Caucasians. Early in our case-control based study also showed the SNP rs2252673was associated with PCOS in Han Chinese. Two of the SNPs rs3786681and rsl7253937(residing in19p13.3) were extracted from our recent genome-wide association studies, which identified19p13.3as a susceptibility locus.Objective:This study was designed to determine whether an association exists between three single nucleotide polymorphism (SNP) variants (rs3786681, rs17253937and rs2252673) of INSR gene and PCOS in Han Chinese in order to identify INSR as a genetic susceptibility factor for PCOS.Methods:Six hundred and seventy two participants consisting of224trios (mother, father and offspring with PCOS) were recruited from the Center for Reproductive Medicine, Shandong University, from July2007to April2013. Serum levels of fasting blood glucose (FBG) and fasting insulin (FINS), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL) and high-density lipoprotein cholesterol (HDL) were measured after12hour empty-stomach. Height and weight were measured while BMI were calculated. Three SNPs (rs3786681, rsl7253937and rs2252673) of INSR gene were amplified by polymerase chain reaction (PCR) and then directly sequenced to screen variants. And the transmitted disequilibrium test (TDT) has been applied for data analysis.Results:In the families based analysis, genotype distributions of the three SNPs were in Hardy-Weinberg equilibrium (p>0.05). After the TDT, the G allele in SNP rs2252673was over transmitted in families(transmitted/non-transmitted=120:88; χ2=4.923, p=0.027).There was a transmitted disequilibrium in rs2252673, which implies the association of INSR and PCOS were independent of population stratification. With respect to the other two SNPs rs3786681and rs17253937, although also detected excessive transfer phenomenon, but they were not statistically associated with PCOS.Conclusion:The study in PCOS nuclear families showed that the SNP rs2252673of INSR gene was associated with PCOS, which further prompt that INSR gene appears to be a susceptibility gene for PCOS.