房间隔缺损患者GATA4基因新突变的识别

Novel GATA4 mutations identified in patients with congenital atrial septal defects

目的 识别房间隔缺损患者新的分子遗传缺陷.方法 收集180例房间隔缺损患者的临床资料和血液标本.以200名健康者作为对照.应用聚合酶链反应扩增GATA4基因的全部外显子,采用双脱氧核苷链末端合成终止法对全部扩增片段进行测序.借助BLAST程序将所测序列与GenBank中的已知序列进行比对以识别基因突变,并用Clustal W软件分析突变氨基酸的保守性.结果 在2例房间隔缺损患者的GATA4基因中各识别出1个新的杂合错义突变,即第21和第87位的密码子分别由GGC和CCG变为GTC和TCG,导致第21和87位的氨基酸分别由甘氨酸和脯氨酸变为缬氨酸和丝氨酸,即G21V和P87S突变.而健康者GATA4基因中未识别出这2个突变.多物种GATA4序列比对显示,突变氨基酸在进化上均高度保守.此外,还识别出1个不改变氨基酸的单核苷酸多态,即c.99 G＞T多态,但是ASD患者与健康者之间基因型和等位基因频率分布差异无统计学意义（GG比GT,x2=0.7556,P=0.3847;G比T,x2=0.7235,P=0.3950）.结论 识别出新的GATA4基因杂合错义突变,有助于房间隔缺损的早期防治.

Objective To identify the genetic defects in patients with congenital atrial septal defects（ASD）. Methods The clinical data and blood samples from 180 unrelated subjects with congenital ASD were collected and evaluated. Two hundred healthy individuals served as controls. The coding exons and the flanking introns of GATA4 gene were amplified by polymerase chain reaction and sequenced using the dideoxynucleotide chain termination approach. The acquired sequences were aligned with the sequences publicized in GenBank by the aid of programme BLAST to identify the sequence variations. Clustal W software was applied for analysis of the conservation of altered amino acids. Results Two novel heterozygous missense GATA4 mutations were identified in 2 out of 180 ASD patients. Namely, the triplet substitutions of GTC for GGC at codon 21 and TCG for CCG at codon 87 were detected, predicting the conversions of glycine into valine at amino acid residue 21（G21V）and proline into serine at amino acid residue 87（P87S）. None of the two mutations were detected in 200 healthy controls. Across-species alignment of GATA4 encoded protein sequences displayed that the mutated amino acids were highly conserved evolutionarily. Additionally,a single nucleotide polymorphism c. 99G 〉 T was observed. However, the polymorphic frequency distribution in ASD cases was similar with that in healthy controls（for genotype GT, x2 = 0.7556, P = 0. 3847; for allele T, x2 = 0.7235, P = 0.3950）. Conclusions Two novel mutations of GATA4 gene are identified in two unrelated ASD patients. This finding provides new insight into the molecular etiology responsible for ASD.