Clinical Analysis Of 1 Case With Large Fragment Deletion Of MLH1 Gene In Lynch Syndrome

Objective:To analysis the clinical features of a case of lynch syndrome with MLH1 gene large fragment deletion,and to summarize the diagnosis and management of this type of Lynch syndrome.Methods:The clinical characteristics,auxiliary examination and diagnostic basis of lynch syndrome with MLH1 gene large fragment deletion in Colorectal Department of Yunnan Cancer Hospital were taken as the research subject.Results:1.A female patient whose elder brother died of colon cancer;2.The patient was diagnosed with colon cancer at the local hospital at the age of 42,and was diagnosed with transverse colon tubular adenocarcinoma and descending colon tubular adenocarcinoma at the age of 51.During the treatment,he was diagnosed with endometrial adenocarcinoma.3.Immunohistochemical detection of mismatch repair protein in postoperative tumor tissues of patients with colon cancer showed that:MSH6(+),MSH2(+),PMS2(-),MLH1(+);4.Gene test results of tumor tissue in patients show that there is High level of Microsatellite Instability(MSI-H);The exon 6-9 of MLH1 deletion.5.Large fragment deletion of MLH1 gene occurred in this patient,and mismatch repair system was decificengt,excluding sporadic colon cancer and familial adenomatous polyposis,which could be diagnosed as Lynch syndrome6.According to the family standard of Lynch syndrome,two patients in the family were diagnosed with colon cancer,which can be identified as the family of Lynch syndrome,and the members of the family should be managed.Summary:1.Lynch syndrome is dominant hereditary colorectal cancer;2.Patients with large MLH1 gene deletions have a higher risk of colorectal cancer.Male patients are mainly metachronous colorectal cancer,and female patients are mainly endometrial cancer.3.The immunohistochemistry of patients with large MLH1 gene large fragment deletion may be the deletion of MLH1 and PMS2 proteins or the deletion of MLH1 protein only;4.Gene detection indicates that a large fragment deletion of the MLH1 gene is deleted,and has a pathogenic mutation,which can be diagnosed as Lynch syndrome;5.According to the standard for family of Lynch syndrome,determine the family of Lynch syndrome and manage its members.