The Study Of The Genotype-phenotype Correlations In Juvenile Polyposis Syndrome

ObjectiveTo characterize the genotype and phenotype of Juvenile polyposis syndrome patients.MethodBy the method of second generation of gene sequencing to seek a family suffered from Juvenile polyposis syndrome with Eight members adopted whole exome sequencing,At the same time,collectted all the clinical data of proband and family members to To characterize the Correlations of genotype and phenotype.Analysis and distributed in the family of JPS and patients scattered possessed the Juvenile polyposis SMAD4 protein expression,Experiment with the newly discovered SMAD4 mutation function of in vitro studies,discover the new mutation effects on cell proliferation and migration ability.ResultsIn eight family members,there are three members possessed the clinical manifestations of Juvenile polyposis syndrome,were detected with 5 members carry genes SMAD4:c.1035C>A(p.Cys345*)mutations,the codon mutations can lead to encoding in 344 for termination codon mutations,protein translation early termination,genetic evaluation for pathogenic mutations.Three members exist MSH3:c.107 T > G gene mutation,double gene mutations.SMAD4 genetic model accord with autosomal dominant mutation.According to bioinformatics combined with genetic analysis,three patients with clinical phenotypes of also jointly with six genes in the hazardous single nucleotide polymorphism loci mutation,five members carry SMAD4 gene mutations also jointly with nine genes in the hazardous single nucleotide polymorphism loci mutation,the locus mutation significance needs further validation.Immunohistochemical results show three members possessed the clinical manifestations of Juvenile polyposis syndrome,SMAD4 are negative or weakly positive expression,31 cases of scattered possessed the Juvenile polyposis,12 patients for weakly positive expression(++),expression rate39 %;13 cases of positive expression(+++),expression rate 42%,6 cases of strong positive expression(++++),expression rate 19%。Western Blot to function in vitro studies of SMAD4 mutations,SMAD4 mutant is SMAD4 wild type group more scattered,irregular shape,morphological diversity,part with tentacles.SMAD4 mutant in vitro migration ability is higher than the wild type SMAD4 groups,statistically significant difference,P <0.0001.SMAD4 mutant is SMAD4 compared to wild type cells,reduce the cell proliferation,was statistically significant,P < 0.05).Conclusion1.This study screening out the gene locus mutation associated with Juvenile polyposis syndrome SMAD4:c.1035C>A(p.Cys345*)mutations,,the mutation led to an early termination codon,caused protein shortened,thus affecting the SMAD4 gene encoding protein product function,and the variation of the downstream truncated variation was reported as pathogenic mutation.Three other members exist MSH3:c.107 T > G mutation,double gene mutations.Two loci did not see the literature,This research is found for the first time.Bioinformatics combined with genetics can use the existing public database quickly and low cost to obtain useful research clues,and use the analysis software to explore the new functions of the gene.2.Immunohistochemical SMAD4 protein can be used as molecular diagnosis of Juvenile polyposis syndrome as an auxiliary index to reflect the genetic status.3.By Western Blot method to clear the truncated SMAD4 mutations can lead to protein,the mutations can lead to cell morphology change,also promote cell migration ability.