Study On Identification Of Pathogenic Genes And The Changes Of Hippocampus MRS And Intelligence Level In GEFS~+

Genetic epilepsy with febrile seizures plus(GEFS~+)is a epilepsy syndrome which diagnosis is based on a family.So far researches have shown that GEFS~+is characterized by autosomal dominant inheritance.Although a large number of GEFS~+pedigrees have been reported,the proportion of pedigrees with gene mutations is less than 20%of the all GEFS~+pedigree.The pathogenic genes and pathogenesis of GEFS~+have not been elucidated.In the early stage of this study,disease-causing genes were screened for the family members of GEFS~+collected.A heterozygous missense mutation c.773A>G(p.H258R)of KCNAB3 gene was found in one family.The site mutation of this gene has not been reported in GEFS~+families before.Evaluation of gene pathogenicity indicated that the effect of this mutation on protein function was likely pathogenic.We.suggest that KCNAB3 may be a new pathogenic gene of GEFS~+in Chinese population.This study intends to verify the mutation of KCNAB3 gene by cellular fuctional method.The fuction of the hippocampus of children with GEFS~+was detected by Magnetic resonance spectroscopy and the intelligence of the children was evaluated by Wechsler intelligence assessment tool in this study.To explore the pathogenesis of GEFS~+and to assessment the hippocampus and cognitive function of children with GEFS~+,in order to provide a new theoretical basis for the study of the etiology and prognosis of GEFS~+.Research objects and methodsObjects:We collected 30 families with GEFS~+between 2016～2019.Methods:Build lentiviral vector plasmids according to the heterozygous missense mutation c.773A>G(p.H258R)of KCNAB3 gene,lentivirus packaging was performed using 292Ta cells,human embryonic kidney cells 293(HEK293)were infected with recombinant lentivirus,whole-cell patch-clamp technique was used to verify the cell function.Hippocampal 1H-MRS spectrum and IQ were measured in 30 probands,and compared with the control group.Results1.The potassium current of HEK293 cell which transfected with wild type KCNA1 recombinant lentivirus plasmid is an active current.The potassium current of HEK293 cell which transfected with wild type KCNA1+wild type KCNAB3 recombinant lentivirus plasmid appear inactivation characteristics.The potassium current of HEK293 cell which transfected with wild type KCNAl+mutation type KCNAB3 recombinant lentivirus plasmid appear more obvious inactivation characteristics.2.The current density of wild type KCNA1 group was 59.674±45.053 pA/pF(n=12),the current density of wild type KCNA1+wild type KCNAB3 group was 35.485±28.695 pA/pF(n=11),and the current density of wild type KCNAl+mutation type KCNAB3 group was 22.607±19.473 pA/pF(n=11).The difference between the three groups was statistically significant(P<0.05).3.The NAA/Cr,Cho/Cr and NAA/(Cho+Cr)value of the hippocampus between the experimental group and the control group showed no significant difference.4.There was no significant difference of intelligence level distribution between the experimental group and the control group(P>0.05).5.The verbal IQ(VIQ)and total IQ(FIQ)of the experimental group were lower than the control group,with significant differences(P<0.05),while the operational IQ(PIQ)was lower than the control group,but there was no significant difference(P>,0.05).Conclusion1.KCNAB3 gene mutation can accelerate the inactivation of potassium ion channels,inhibit potassium ion current,maybe improve neuronal excitability,and promote the generation of epilepsy or convulsion.2.KCNAB3 gene may be a new pathogenic gene of GEFS~+in Chinese population.3.In this study,the changes of hippocampal MRS in children with GEFS~+were not significant.4.In this study,the verbal intelligence(VIQ)and total intelligence(FIQ)of GEFS~+children were lower than the control group,while the intelligence level distribution and operational intelligence(PIQ)showed no difference with the control group.