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 di-deoxynucleotide 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, χ(2) = 0.7556, P = 0.3847; for allele T, χ(2) = 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.