RESUMO
BACKGROUND: With prevalence up to 4%, Ventricular Septal Defect (VSD) is one of the leading causes of neonatal deaths. VSD is a common complex genetic disorder that has been associated with many genetic determinants. Variants from genes for the transcription factors including T-Box TBX5 and NFATc1 (nuclear factor of activated T cells, cytoplasmic 1), Vascular endothelial growth factor (VEGF), ISLET1 (encoded by the ISL1 gene) and enzyme MTHFR, a methylene tetrahydrofolate reductase were selected. Genetic risk score (GRS) is a widely accepted approach used to convert the genetic data into prediction and assessment tool for disease susceptibility. METHODS: A total of 200 participants were recruited for the current study, 100 VSD patients and 100 controls. Genotyping of the ISL1: rs1017, NFATc1: rs7240256, VEGF: rs36208048, TBX5: rs11067075, and MTHFR: rs1801133 variants was performed using tetra primer ARMS PCR and PCR-RFLP. For the statistical analysis, the software SPSS version 23 was used. Genotypic frequencies of cases and controls were calculated using chi-square (χ²) whereas allelic frequencies were calculated by using the SNPStats tool. The association of GRS quartiles with VSD was examined using binary logistic regression. Adjusted p-value 0.01 was used as significance threshold for all analyses. RESULTS: The ISL1 (OD: 0.242, CI: 0.158-0.37, p-value: 2.15 × 10- 4 :), NFATc1 (OD: 2.53, CI: 1.64-3.89, p-value: 2.11 × 10- 5), TBX5 (OD: 2.24, CI: 1.47-3.41, p-value:1.6 × 10- 4) and MTHFR (OD: 10.46, CI: 5.68-19.26, p-value: 2.09 × 10- 9:) variants were found to be in association with VSD. In contrast, the VEGF (OD: 0.952, CI: 0.56-1.62, p-value: 0.8921) variant did not show significance association with the VSD. For cases, the mean GRS score was 3.78 ± 1.285 while in controls it was 2.95 ± 1.290 (p-value: 0.479, CI: 0.474-1.190). Comparison of GRS between cases and control showed that mean GRS of cases was 1.90 ± 0.480 while in controls it was 1.68 ± 0.490 (p-value: 0.001, CI: 0.086-0.354). Higher quartiles were more prevalent in cases whereas lower quartiles were more prevalent in controls. CONCLUSION: GRS of these five loci was strongly associated with VSD. Moreover, genetic risk score can provide better information for the association between variants and disease as compared to a single SNP. We also illustrated that the cumulative power of GRS is greater over the single SNP effect. This is a pilot scale study with a relatively small sample size whose findings should be replicated in a larger sample size for the unique local Pakistani population.
