Analysis Of The BRCA1/2 And MSH2 Genes Mutations In A Hereditary Ovarian Carcinoma Family

Objective:To vestigate the carcinogenic mechanisms of a hereditary ovarian carcinoma family, sequencing and analysis the exons of the BRCA1/2 and MSH2 genes which are internationally recognized that are associated with familial ovarian cancer in the blood of all women in this family,detecting whether there is a meaningful missense mutation,If can find mutation points, we will analysis the possible mechanism in the pathogenesis of the familial ovarian cancer, then make individual follow-up counseling and preventive treatment to the high-risk women of this family.Methods: Asking in details about the proband’s clinical history, auxiliary examination results and the family information. Drawing the pedigree,Then analyze the characteristics of the disease. Collecting the blood sampling to all the alive female members in this family,extracting the pathological tissue samples to patient who have died,at the same time,taking 2 sporadic ovarian cancer patients’ blood specimens with the same pathological type as the control group.Extracting the DNA,then use the PCR to amplify,make direct sequencing comparision to the product of the PCR,in order to explore whether there is a meaningful missense mutations in this family,Research and forecast to the result in mutations of protein structure and molecular conformation.Result:1.In this family, there are three people clearly diagnosised of ovarian cancer,whose pathology were all ovarian serous cystadenocarcinoma,consistent with the report in the related literature of the hereditary ovarian cancer pathological types.compare with the sporadic ovarian cancer,ovarian serous cystadenocarcinoma has an earlier age of onset and easy to have a transfer and tumor recurrence.2.We found eight mutations in the fully sequenced genes of BRCA1,three of them are nonsense mutations(2314C>T,2543T>C,4540T>C);Two of the nonsense mutations have been recorded,respectively associated with cervical cancer(2844C>T)and endometriosis(3345A>G);And found 3 new mutations,that is no been reported.In the three new mutations,3780A>C,7469A>G change the amino acid,however the3326A>T causes the Arg turned to termination codon.Three patients who diagnosised of ovarian cancer all has 3326A>T.3.We found 7 mutations in the fully sequenced genes of BRCA2,five of them are nonsense mutations(3623A> G,4034T> C,4790A> G,7469A> G,6740G> C); One mutation has not been recorded(1716T>A);One mutation has record(1342A>C),which is related to the breast cancer.Three patients who diagnosised of ovarian cancer all has 1342A>C.4.We found 2 mutations in the fully sequenced genes of MSH2(1380C>A,2011A>G),which is only in one patients with ovarian cancer,the rest of the women detection are normal.5.Sequencings of the BRCA1/2, MSH2 genes of ovarian serous cystadenocarcinoma patients who are suffering without a family history are normal.6. In the genetic testing of the Ⅲ generation of the women, 4 people who carried BRCA2 gene 1342A>C,one of whom also carry BRCA1 gene 3326A> T,At present,the four follow-up are normal.Conclusion: According to analysis of genetic testing, This family is a typical hereditary ovarian carcinoma family,sequencing of heterozygous mutation 3326A> T in the BRCA1 gene and heterozygous mutation 1342A> C in the BRCA2 gene are likely to be the causative genes of the familial hereditary ovarian cancer. The existing researchs and investigations suggest that the heterozygous mutation 1342A>C in the BRCA2 gene is highly correlated with the occurrence of breast cancer, heterozygous mutation 3326A>T in BRCA1 gene lead the site of arginine mutation for the termination codon, resulting in the termination of translation of amino acids and the protein shorter, dramatical changes in the conformation of molecular model. From this speculation, Both the BRCA1 gene 3326A>T and BRCA2 gene 1342A>C interact synergistically leads to the occurrence of ovarian cancer in this pedigree. Do genetic testing to Screen for suspected oncogene in the whole family of women, In order to know who is at risk of cancer in the family, And follow up, To achieve early detection, early diagnosis, early treatment, and do preventive treatment when necessary and feasible.In Europe, The detection of BRCA1/2 mutations has become an importantscreening method for population at high risk of ovarian cancer. But in China, the study on the mutations of BRCA1/2 gene in the peripheral blood of Patients with high risk family ovarian cancer and sporadic ovarian cancer is not very deep. At present,there is no in-depth report on the common mutations of BRCA1/2 genes in Chinese hereditary ovarian carcinoma family. This clinical study was undertaken in a typical hereditary ovarian cancer pedigree.The two relative fixed mutation sites of BRCA1/2 were found by gene sequencing,A useful exploration and attempt was made for the detection of oncogene in the Chinese hereditary ovarian carcinoma family.