Clinical Manifestation And Gene Mutation Analysis Of Tuberous Sclerosis

Research backgroundTuberous Sclerosis Complex（TSC）is a genetic disease that implicates almost all tissues and organs throughout the body,with extensive hamartoma formation or abnormal growth of normal tissues.It conforms to autosomal dominant inheritance,the incidence is about 1/10000-1/6000,and the age of onset covers the infant to postpubescent.TSC1 and TSC2 genes are two TSC pathogenic genes detected so far,but only about 30%-40%of patients are found to be inherited from the family,Most cases are spontaneous mutations.The consequent of TSC interrelated to the severity of the disease phenotype.Patients with mild clinical manifestations usually have a good prognosis and have the same life expectancy as normal people;however,for those who are severely affected,the outcome usually is bad.In view of the heterogeneity of disease severity,genetic testing is now an important tool for diagnosis,especially when clinical manifestations are insufficient to confirm the diagnosis.However,hot spot mutations in TSC have not been found yet.In spite of researcher at home and abroad carried out many trials on its clinical phenotype and genotype,no clear correlation rules have been found so far.We are trying to find the mutation mode and location of TSC and its relationship with the clinical phenotype so as to help its early diagnosis,outcome forecasting and personalized therapy.ObjectiveCollect the data of 10 children with TSC from our hospital,and and use the way of gene sequencing to anal)ze the exon gene sequencing of the children and their family members,analyzing the types of gene mutations,looking for the mutation mode and location of tuberous sclerosis and its relationship with the clinical phenotype.MethodsWith the agreement of the children’s fiduciary,gathering the cranial imaging,clinical data and visceral color ultrasound and other related examination results of 10 children with TSC and their relatives.All of them were from the inpatient and outpatient department of the Pediatric Department of the First Affiliated Hospital of Zhengzhou University.Collecting the blood specimen of the child and his or her family members,and abstracting the DNA from the blood of the children with a designated kit.And then the extracted DNA is purified,processed,modified,and amplified after a series of steps to obtain desired target gene library.Sequencing the gene by Shenzhen Biological Company,then filter,compare and perform database analysis and integration of the sequencing results to hunt for meaningful gene mutation sites and types.Perform Sanger sequencing of clinically significant gene mutation sites and the corresponding gene sites of their relatives.ResultsEpilepsy was the first symptom of all the 10 children in this study,and the age of onset was from 0 to 36 months.Among them,9 cases had skin damage,8 cases had intracranial calcification,5 cases had mental retardation,and 1 case had kidney damage,10 cases of children had no heart,lung or eye disease.The proband in family 1 detected c.2074C>T on TSC1 gene on chromosome 9,which was a reported pathogenic mutation.None of his parents had abnormal mutations at this site.The mutation was a nonsense mutation.The c.2545+10C>T heterozygous splicing mutation was found in the TSC2 gene of the proband in family 2,whose pathogenicity has not been reported in the literature,and it was a new pathogenic mutation.Her father was heterozygous at this locus,and her mother had no abnormalities at this locus.The c.2497C>T in the TSC1 gene of chromosome 9 was detected in the proband in family 3,which was a known damaging mutation.His mother was heterozygous at this locus,so was his sister,and the father did not find any variation at this locus.The proband in family 4 detected the c.4375C>T in the TSC2 gene.Whether it is pathogenic has not been reported in the past literature,in our research it is a pathogenicity mutation.His mother,sister and brother also detected c.4375C>T heterozygous mutation on TSC2.TSC mutation is not detected in the proband 5 family of the 10 families.The proband in family 6 had a c.932-936del base deletion mutation in the TSC2 gene,a pathogenic mutation that had been detected.The proband in family 7 had a c.1659C>G nonsense mutation in the TSC2 gene.It was a new pathogenic mutation.The father,mother,eldest sister and second sister had no mutations,and it is a spontaneous mutations from the proband.The proband from family 8 had c.5238₅255del（p.His1746_Arg1751del）base deletion mutation in TSC2,which was a reported pathogenic mutation.A large fragment of 16p13.3（chr16:2128073-2130296）*1 was detected in probands from the proband from family 9,which was a new pathogenic mutation.There was a c.2714G>C missense mutation in TSC2 in the proband of family 10,which was a new pathogenic mutation.Conclusion1.A total of 5 cases of new mutations were found in this study,namely TSC2 c.2545+10C>T splicing mutations in probands of family 2,TSC2 c.4375C>T of probands of family 4 and TSC2 c.1659C>G of probands of family 7 heterozygous nonsense mutation,TSC2 c.2714G>C heterozygous missense mutation of probands of family 10.The 2.22Kb 16p13.3（chr16:2128073-2130296）*1 fragment of family 9 proband is missing.The above mutations have not been reported in human gene IX databases at home and abroad.They are new pathogenic mutations,which provides research data for the domestic diagnosis of TSC;2.Compared with TSC1,individuals with TSC2 mutations have more severe clinical symptoms,and are more likely to have mental retardation,and are more difficult to control epilepsy seizures;the clinical manifestations of the same family members with the same mutation are significantly heterogeneous.