GATA4 mutation and congenital cardiovascular diseases: importance of phenotype and genetic background clarification

GATA 4 Deletions Associated with Congenital Heart Diseases in South Brazil

The normal development of the heart comprises a highly regulated machinery of genetic events, involving transcriptional factors. Congenital heart disease (CHD), have been associated with chromosomal abnormalities and copy number variants (CNVs). Our goal was to investigate through the multiplex ligation-dependent probe amplification (MLPA) technique, the presence of CNVs in reference genes for normal cardiac development in patients with CHD. GATA4 , NKX2-5 , TBX5 , BMP4 , and CRELD1 genes and 22q11.2 chromosome region were analyzed in 207 children with CHD admitted for the first time in a cardiac intensive care unit from a pediatric hospital. CNVs were detected in seven patients (3.4%): four had a 22q11.2 deletion (22q11DS) (1.9%), two had a GATA4 deletion (1%) and one had a 22q11.2 duplication (0.5%). No patients with CNVs in the NKX2-5 , TBX5 , BMP4 , and CRELD1 genes were identified. GATA4 deletions appear to be present in a significant number of CHD patients, especially those with septal defects, persistent left superior vena cava, pulmonary artery abnormalities, and extracardiac findings. GATA4 screening seems to be more effective when directed to these CHDs. The investigation of CNVs in GATA4 and 22q11 chromosome region in patients with CHD is important to anticipating the diagnosis, and to contributing to family planning.

A novel mutation in exon 1 of GATA4 in Egyptian patients with congenital heart disease

BACKGROUND/AIM

Congenital heart disease (CHD) is a common birth defect. Many studies have reported GATA4 mutations in patients with CHD, mainly septal defects. This study aimed to investigate the GATA4 exon 1 mutation in Egyptian patients with isolated congenital heart defects as a possible causative mutation.

MATERIALS AND METHODS

Screening for mutations or any sequence variations in exon 1 of the GATA4 gene was carried out by PCR amplification followed by direct sequencings in 165 Egyptian patients with different nonsyndromic congenital heart diseases and 93 controls who were matched in terms of age and sex. Thorough clinical assessments were done for all subjects, along with X-ray, 2D echocardiography, and Doppler examinations.

RESULTS

The most common CHD among our cases was isolated ventricular septal defect (VSD) in 47.3% (78/165), followed by isolated atrial septal defect. A novel nonsynonymous sequence variation in fragment 2 (P193H) of exon 1 of GATA4 was detected in 15 (9.1%) of the subjects with septal defects. This mutation was not seen in any of the control group subjects.

CONCLUSION

There is a high prevalence of exon 1 GATA4 mutation (9.1%) in our study compared to other studies in different populations, which may correlate with different ethnic populations.

The effects of transfection reagent polyethyleneimine (PEI) and non-targeting control siRNAs on global gene expression in human aortic smooth muscle cells

BACKGROUND

RNA interference (RNAi) is a powerful platform utilized to target transcription of specific genes and downregulate the protein product. To achieve effective silencing, RNAi is usually applied to cells or tissue with a transfection reagent to enhance entry into cells. A commonly used control is the same transfection reagent plus a "noncoding RNAi". However, this does not control for the genomic response to the transfection reagent alone or in combination with the noncoding RNAi. These control effects while not directly targeting the gene in question may influence expression of other genes that in turn alter expression of the target. The current study was prompted by our work focused on prevention of vascular bypass graft failure and our experience with gene silencing in human aortic smooth muscle cells (HAoSMCs) where we suspected that off target effects through this mechanism might be substantial. We have used Next Generation Sequencing (NGS) technology and bioinformatics analysis to examine the genomic response of HAoSMCs to the transfection reagent alone (polyethyleneimine (PEI)) or in combination with commercially obtained control small interfering RNA (siRNAs) (Dharmacon and Invitrogen).

RESULTS

Compared to untreated cells, global gene expression of HAoSMcs after transfection either with PEI or in combination with control siRNAs displayed significant alterations in gene transcriptome after 24 h. HAoSMCs transfected by PEI alone revealed alterations of 213 genes mainly involved in inflammatory and immune responses. HAoSMCs transfected by PEI complexed with siRNA from either Dharmacon or Invitrogen showed substantial gene variation of 113 and 85 genes respectively. Transfection of cells with only PEI or with PEI and control siRNAs resulted in identification of 20 set of overlapping altered genes. Further, systems biology analysis revealed key master regulators in cells transfected with control siRNAs including the cytokine, Interleukin (IL)-1, transcription factor GATA Binding Protein (GATA)-4 and the methylation enzyme, Enhancer of zeste homolog 2 (EZH-2) a cytokine with an apical role in initiating the inflammatory response.

CONCLUSIONS

Significant off-target effects in HAoSMCs transfected with PEI alone or in combination with control siRNAs may lead to misleading conclusions concerning the effectiveness of a targeted siRNA strategy. The lack of structural information about transfection reagents and "non coding" siRNA is a hindrance in the development of siRNA based therapeutics.