| Background and ObjectivePolycystic ovary syndrome(PCOS)is a common disease in woman with symptoms of endocrine and metabolic disorder.The prevalence of woman with childbearing age is 6%-10%.It is characterized by sparse ovulation or anovulation,hyperandrogenism,polycystic changes of the ovary,and menstrual disorders.In addition to affecting woman's ability of reproduction,a large number of studies have found that it may also increase the risk of obesity,insulin resistance(IR),type 2diabetes(DM2),and cardiovascular disease.Although its pathogenesis remains unclear,accumulated data suggest that PCOS is a complex disease involving both genetic and environmental factors.At present,many scholars believe that the pathogenesis of PCOS is related to epigenetics,but the specific mechanism of action is determined.Epigenetics is a molecular mechanism that changes in the phenotype when the DNA sequence is not altered.Epigenetic studies include: DNA methylation,histone modifications,X chromosome inactivation(XCI)and genome imprinting.It is a process by which methyl groups are added to the cytosine in DNA sequence,forming the 5-methylcytosine.It is generally considered that DNA methylation will inhibit the binding of transcription factors to DNA sequence,thereby inhibiting gene expression.At present,studies have shown that changes in the DNA methylation of some candidate genes of PCOS are closely related to the pathogenesis of the disease.In the previous period,we investigated 1035 women and found that menstrual disorders in the A,B,AB,and O blood groups were 64.3%,59.8%,61.5%,and 81.3%respectively,and there were statistically significant differences between the O blood group and others.This finding has not been reported at home and abroad.Menstrual disorders are a basic clinical manifestation of polycystic ovary syndrome,so we have to speculate that there may be some connection between the ABO blood group gene and pathogenesis of PCOS.The ABO blood group gene is located on chromosome 9(9q 34.1-34.2).There are three major alleles at the ABO blood group locus,they are A,B,and O.It has been found that the methylation of the CpG site in the ABO blood group gene promoter region is associated with many diseases.However,whether the methylation status of ABO blood group genes is related to the pathogenesis of PCOS has not been reported.Based on the above background we propose hypothesis,the methylation status of ABO blood group gene promoter region plays an important role in the development of PCOS.This study will explore the pathogenesis of PCOS from a new perspective.By then,it can provide a theoretical basis for the pathological mechanism of PCOS,which is helpful for early diagnosis of PCOS and prevention of long-term complications of PCOS.Research object1.PCOS patientsWe selected 20 patients with PCOS randomly who were diagnosed in the department of endocrinology of People's Hospital of Henan Province from September2016 to December 2017,with an average age of 24.60 ± 4.68 years old.PCOS diagnostic criteria is based on the 2003 European Society of Human Reproductive and Embryological/American Reproductive Medical Society(ESHRE/ASRM)Rotterdam Expert Meeting and have been diagnosed by clinical examination(e.g.symptom signs,ovarian ultrasound,biochemical tests,endocrine hormonemeasurements).2.Control groupRandomly selected 20 healthy females who matched the age and body mass index of PCOS patients with conditions of non-taking hormone drugs,endocrine diseases as well as hypertension during the past 3 months,and the average age was23.35 ± 3.52 years old.All the subjects studied were Han Chinese in northern China,who lived in Henan for a long time and had no blood relationship with each other.The study protocols were approved by the Ethics Committee of Human Research of People's Hospital of Henan Province and Zhengzhou University.What's more,all subjects have signed informed consent.Research methods1.ABO blood type was detected by slide methodThe ABO blood group of all the subjects was detected by slide method.2.Detection of ABH antigen on red blood cellsDetection of A and B antigens on the surface of red blood cells uses monoclonal anti-human A and B mouse antibodies were used as the first antibodies and anti-Mouse IgG,H&L Chain Specific Fluorescein(FITC)Conjugate as the second antibody.Measurement of H antigen used Lectin from Ulex europaeus agglutinin-1Fluorescein Conjugate(UEA-1).Flow cytometry was applied for detecting Mean fluorescence intensity.3.The mRNA expression levels of ABO geneq-PCR was used to detect and analyze the mRNA expression of ABO gene in PCOS patients and controls.4.The DNA methylation level of ABO blood group gene promoterThe methylation level of 28 CpG loci in the promoter region of ABO blood group was detected by MethyTarget region enrichment methylation sequencing method.All experimental data for this study used SPSS 21.0 and GraphPad Prism 5statistical software to analysis and draw charts.All quantitative data were expressed asmean±SD,and the quantitative data between the two groups were compared using two independent sample t tests,the quantitative data between the four groups were compared by the single factor analysis of variance.P values less than 0.05 were considered statistically significant.Result1.The subject's blood group was divided into A,B,AB,and O blood types using the slide method.Among 20 patients with PCOS,6 were O blood type,9 were A blood type,4 were B blood type,and 1 was AB blood type.Among 20 healthy controls,8 were O blood type,5 were A blood type,4 were B blood type,and 3 were AB blood type.2.The expression of B antigen on the surface of red blood cells in patients with B blood type PCOS was significantly lower than that in controls(P<0.05),but there was no significant difference in the expression of H antigen compared with controls(P>0.05).The expression of H antigen on the surface of red blood cells in patients with O blood type PCOS was significantly lower than that in controls(P<0.05);There was no statistical difference between PCOS patients with A and AB blood type and controls in the expression of A,B,and H antigens on the surface of red blood cells(P>0.05).3.The mRNA expression of ABO gene in B blood type PCOS patients was significantly lower than that in controls(P<0.05).The mRNA expression level of ABO gene in O blood type PCOS patients was significantly lower than that in controls(P<0.001).There was no significant difference in the mRNA expression of ABO between PCOS patients with A and AB blood type and controls(P>0.05).4.The average methylation level of CpG4 loci was lower in the PCOS patients than that in controls.The average methylation water of the other 27 CpG loci was higher in the PCOS patients than that in controls,but there was no statistical significance(P>0.05).The average methylation water of all CpG loci in group PCOS group of B blood group was higher than that of the healthy group,only the average methylation level of the four loci of CpG16,CpG18,CpG19 and CpG26 had significant difference,and the difference was statistically significant(P<0.05).Theaverage methylation level of the 28 CpG loci in O blood group,A blood group and AB blood group was different from that of the healthy control group,but the difference was not statistically significant(P> 0.05).ConclusionThe decrease of ABO gene expression in B blood group PCOS is related to the hypermethylation of ABO gene promoter region.It is necessary to expand the sample for further verification.The results showed that hypermethylation of ABO gene is a potential factor for PCOS susceptibility. |
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