Molecular Genetic Study on HAND2 Gene Promoter in Ventricular Septal Defect

Ventricular septal defect (VSD), the most common type of congenital heart disease (CHD), is primarily caused by cardiac dysplasia. Heart and neural crest derivatives expressed 2 (HAND2) participates in developing the right heart. The loss of HAND2 expression in humans is closely connected with ventricular septal defects. We used a case-control study to analyze the genetic variations in the HAND2 promoter region in VSD patients and controls. Some statistical analysis methods were used to analyze the association of single nucleotide polymorphisms (SNPs) with VSD. The dual-luciferase reporter assay and electrophoretic mobility shift assay (EMSA) were used to conduct functional analysis and molecular mechanism study of genetic variations. Through sequencing, we identified nine genetic variants in patients with VSD. The SNP rs2276940 G>T and rs2276941 G>A were associated with an increased risk of VSD. The dual-luciferase reporter assay showed that SNP rs2276940 G>T and rs138531627 C>G decreased the transcriptional activity of the HAND2 promoter. Transcription factors (TFs) predicting suggested that all three SNPs may change the binding of TFs. The result of EMSA showed that rs138531627 C>G may create a new binding site for TFs while rs2276940 G>T enhanced the binding affinity for TFs. These results indicated that genetic variants of the HAND2 promoter may increase the risk of VSD, and the molecular mechanism may be the change of the binding affinity of TFs.