Ventricular septal defects (VSD) are the most common congenital heart defects (CHD). Studies have documented that ISL1 has a crucial impact on cardiac growth, but the role of variants in the ISL1 gene promoter in patients with VSD has not been explored. In 400 subjects (200 isolated and sporadic VSD patients: 200 healthy controls), we investigated the ISL1 gene promoter variant and performed cellular functional experiments by using the dual-luciferase reporter assay to verify the impact on gene expression. In the ISL1 promoter, 5 variants were found only in VSD patients by sequencing. Cellular functional experiments demonstrated that three variants decreased the transcriptional activity of the ISL1 promoter (P < 0.05). Further analysis with the online JASPAR database demonstrated that a cluster of putative binding sites for transcription factors may be altered by these variants, possibly resulting in change of ISL1 protein expression and VSD formation. Our study has for the first time identified novel variants in the ISL1 gene promoter region in the Han Chinese patients with isolated and sporadic VSD. Additionally, the cellular functional experiments, electrophoretic mobility shift assay, and bioinformatic analysis have demonstrated that these variants significantly alter the expression of the ISL1 gene and affect the binding of transcription factors, likely resulting in VSD. Therefore, this study may provide new insights into the role of the gene promoter region for a better understanding of genetic basis of the formation of CHD and may promote further investigations on mechanism of the formation of CHD.
Novel and Functional DNA Sequence Variants within the GATA6 Gene Promoter in Ventricular Septal Defects
