A Study On Pathogenic Gene Mutations In Patients With Premature Ovarian Insufficiency

Premature ovarian insufficiency(POI)is a clinical syndrome that affects women under 40 years of age and is characterized by at least a 4 month history of primary or secondary amenorrhea and levels of serum follicle stimulating hormone(FSH)>25 IU/L on two occasions>4 weeks apart.POI is a highly heterogeneous disorder.It is caused mainly by factors of genetics,infectious,autoimmune or iatrogenic.Among them,genetic factors,as one of the important causes in the pathogenesis of POI,exist not only in patients with a positive family history of POI,but also play an important role in the pathogenesis of sporadic POI ones.Owning to the irreversibility of decline of female ovarian function,there is no effective ways to restore or improve the ovarian function of these patients.Therefore,a focus of study on genetic etiology of POI patients will help us to clarify an accurate genetic diagnosis,to make a deeper understanding of the molecular genetic basis of ovarian and follicular development.And it is also a key step to achieve goals on screening for high-risk potential female groups and early diagnosis and treatment for POI.In Chapter Ⅰ,we aimed to analyze the genetic cause in two affected sisters diagnosed with POI and their biological parents with normal clinical phenotype from a highly consanguineous Chinese Han family.Whole-exome sequencing(WES)was performed,and bioinformatics analysis was used to determine the potential genetic cause of POI in this family.A homozygous gross deletion mutation that includes in the SYCE1 gene region that relates to a process of meiosis was harbored by the proband and her affected sister,whereas both parents had heterozygous deletion.And it was consistent with a pattern of autosomal recessive inheritance.And this consanguineous Chinese familial study revealed that a gross deletion includes the SYCE1 gene region associated with premature ovarian insufficiency.In Chapter Ⅱ,WES was used to analyze genetic factors within another Chinese POI pedigree with a non-consanguineous marriage.A novel heterozygous missense mutation in HFM1(c.3470G>A)associated with POI was identified by WES.This mutation was heterozygous in the affected family members and was absent in the unaffected family members.HFM1 is a meiosis-specific gene and encodes a DNA helicase essential for meiotic homologous recombination.HFM1 gene expresses in germline tissues and it plays an important role in DNA damage repair and regulation in gene during the process of meiosis.The results of the minigene assay revealed that the mutation in HFM1(c.3470G>A,p.C1157Y)changed the splicing repertory in two cell lines.We concluded that this novel heterozygous splice-altering mutation in HFM1 may be a cause of premature ovarian insufficiency.In Chapter Ⅲ,we explored and made a correlation analysis between GJA4 gene and POI in Chinese population.GJA4 gene screening was performed in 95 sporadic POI patients and 180 control groups in Chinese population.In our study,we found that there was no correlation between GJA4 gene and Chinese sporadic POI patients.GJA4 mutations may not a common cause for Chinese POI patients.In Chapter Ⅳ,we aimed to analyze the clinical characteristics of 51 Chinese patients with POI and explored the related genetic etiology.Clinical phenotypes and characteristics were summarized and subsequently WES was performed and bioinformatics tools were used to analyze the potential genetic causes of the affected ones with POI of Chinese origin.Multiple known or new pathogenic gene mutations related to the pathogenesis of POI were found in some patients.The results in our study will be meaningful for developing research methods focusing on genetic counseling,risk prediction and intervention.