A Novel Mutation Of GATA4(K300T)Associated With Familial Atrial Septal Defect

CHD is one of the most prevalent birth defects and leads to serious morbidity and mortality,affecting approximately 8–12 live births per 1000.ASD,comprising 30–40% of all adult CHDs,is anatomically characterized by an interatrial septum that is defective or absent,causing blood to flow directly between the atria of the heart.Till date,more than 10 genes that encode transcription factors or cofactors(NKX2.5,GATA4,TBX5,TBX20,and CITED2),structure proteins of the sarcomere(ACTC1,MYH6,MYH7,and MYBPC3),and a metalloprotease(TLL1)have been implicated in inherited ASD.Among these genes,GATA4 and NKX2.5 were disease genes with highpenetrance mutations.The GATA4 gene,consisting of seven exons,encodes a zinc-finger transcription factor GATA4,which recognizes the GATA motif presented in the promoter of many genes involved in cardiogenesis.According to the Human Gene Mutation Database(HGMD),123 mutations in GATA4 have been reported in cases of congenital heart disease(CHD),such as the tetralogy of Fallot(ToF),atrial septal defect(ASD),ventricular septal defect(VSD),atrioventricular septal defect(AVSD),and dilated cardiomyopathy(DCM).The GATA-binding protein 4 gene(GATA4)encodes a zinc-finger transcription factor that plays a key role in embryogenesis and cardiac development.We studied a fourgeneration Chinese ASD family and identified a novel GATA4 mutation(c.A899 C,p.K300T)in all surviving affected members and two carriers with incomplete penetrance.This mutation has not been described in previous reports or presented in our control cohorts and databases,including the Database of Single Nucleotide Polymorphisms(dbSNP),the Exome Variant Server Database(EVSD),and the HGMD.Bioinformatics programs(PolyPhen-2,SIFT,and MutationTaster)predicted the mutation to be deleterious.The lysine at the mutation position was highly conserved from Drosophila to humans and was recognized as a methylation location in the GATA4 protein.The involvement of the lysine methylation in cardiogenesis by attenuating the transcriptional activity of GATA4 in mice has been previously examined.Objective:To identify the disease-causing gene mutation of a X-linked FDCM pedigree spanning four generations and consisting of 68 family members.Methods:We studied the ASD pedigree using a combined of whole exome sequencing(WES)and multiple sequence alignments and bioinformatic prediction of mutation.Results:1.A novel nonsynonymous variant(c.A899 C,p.K300T)in the exon4 of GATA4 was detected in all affected family members(II:6,III:4,III:5,III:11,III:26,III:31,IV:1,IV:4)and two unaffected carriers(II:10,III:1).This variant,with no record in dbSNP,EVSD,and HGMD databases,was not detected by high-resolution melting analysis in our 220 control cohorts.2.Whole-exome sequencing of the patient IV:4 was applied to identify variants in 27 other congenital heart malformation genes and 130 Mendelian cardiac-disorder-associated genes.A total of 36,412 SNPs and 2342 indels were identified by sequencing,with 83 SNPs and 389 indels passing the filtering criteria.3.One SNP in ZASP and two indels in ACTN2 and MICA,respectively,were detected in 157 genes,but none of these variants cosegregated with affected members.Other genes containing passthrough SNPs and indels were checked against the published literature and no CHD-associated gene was found.4.Alignments of GATA binding protein family members from Drosophila to human revealed that the affected amino acid is evolutionarily conserved.The p.K300 T variant was predicted to be probably damaging,to affect protein function,and to be disease-causing(probability value: 0.999)by PolyPhen-2,SIFT,and MutationTaster,respectively.These predictions support the notion that the variant is detrimental and contributes to the pathogenesis of ASD and VSD in this family.Conclusions:1.A familial atrial septal defect pedigree including 68 family members in four generations is described in this article.2.We identified a novel mutation(c.A899 C,p.K300T)in GATA4 gene.Our study broadens the mutation spectrum of the GATA4 gene and reveals for the first time a mutation at the methy lation position of GATA4 associated with ASD.3.The causal gene for familial atrial septal defect can be identified by WES in a short time.