Role of endothelial nitric oxide synthase VNTR (intron 4 a/b) polymorphism on the progression of renal disease in autosomal dominant polycystic kidney disease

Association of NOS3 (rs 2070744) and SOD2Val16Ala (rs4880) gene polymorphisms with increased risk of ESRD among Egyptian patients

BACKGROUND

Chronic kidney Failure (CKD), particularly End-Stage Renal Disease (ESRD), may be serious ill-health related to a high death rate. Uremic syndrome leads to increased oxidative stress, inflammation, and dyslipidemia. Our study aimed at identifying the association of NOS3 (rs 2070744) and SOD2 Val16Ala (rs4880) gene polymorphisms within ESRD Egyptian patients.

METHODS

This work was conducted on 100 ESRD and 16 CKD Egyptian patients who were compared to 100 healthy controls. DNA was genotyped for these variants using the (T-ARMS-PCR) technique.

RESULTS

ESRD patients showed a significant association of the genotype of NOS3 gene polymorphism compared with healthy controls (P = 0.032). In the contrast, the present study revealed that no statistically significant differences were found among the CKD, ESRD, and control groups as regards the SOD2 genotypes (P = 0.064).

CONCLUSIONS

Our findings indicated a significant association between NOS3 (rs 2070744) gene polymorphism and increased risk of ESRD and CKD among Egyptian patients.

Could the interaction between LMX1B and PAX2 influence the severity of renal symptoms?

Nail Patella syndrome (NPS) is a rare autosomal dominant disease characterized by varying degrees of patella, nail, and elbows dysplasia and also ocular and renal congenital abnormalities. The renal involvement, ranging from hematuria and proteinuria to end-stage renal disease, is present in 22-60% of NPS cases. Heterozygous variants in LMX1B are known to be responsible of NPS and it has been hypothesized that the variable expressivity is due to the interaction of LMX1B with other developmental genes. We reported a case of co-presence of LMX1B and PAX2 variants in a child with extrarenal manifestation of NPS and end-stage renal disease but congenital bilateral renal hypodysplasia and vesicoureteral reflux. The LMX1B variant was de novo, whereas the PAX2 variant was inherited from the mother that had bilateral renal hypoplasia although in presence of only a mild chronic kidney disease. The molecular interaction between LMX1B and PAX2 has been already reported in vitro and this finding suggest that the worst renal NPS phenotype of our patient could be due to the defective expression of these two genes during nephrogenesis. In conclusion, our finding suggests that PAX2 may act as modifier gene in Nail Patella phenotype.

Polymorphism of the endothelin-1 gene (rs5370) is a potential contributor to sickle cell disease pathophysiology

Sickle cell disease has been shown to demonstrate extensive variability in disease severity among and between individuals, the variability highlighted by differing genetic haplotypes. Despite the abundance of reports of functional significance due to polymorphisms of endothelial nitric oxide synthase (eNOS) and endothelin-1 (ET-1) genes, the role of these polymorphisms in mediating sickle cell disease pathophysiology among African Americans is presently unclear. To deconvolute their potential significance among African Americans with sickle cell disease, we examined the genetic diversity and haplotype frequency of eNOS and ET-1 polymorphisms in disease (n = 331) and control (n = 379) groups, with a polymerase-chain reaction restriction fragment length polymorphism assay. We report that genotypic and allelic frequencies of eNOS variants are not significantly different between groups. eNOS homozygote mutants, which had been shown to have clinical significance elsewhere, showed no statistical significance in our study. On the other hand, and contrary to previous report among Africans with sickle cell disease, the endothelin-1 homozygous mutant variant showed significant difference in genotypic (p = 2.84E-12) and allelic frequencies (p = 2.20E-16) between groups. The most common haplotype is the combination of T786C homozygote wild-type variant with homozygote mutant variants of G5665T (ET-1) and Glu298Asp (eNOS). These results show that endothelin-1 (rs5370) polymorphism, rather than endothelial nitric oxide synthase polymorphism might play a significant role in disease severity or individual clinical outcomes among African Americans with sickle cell disease. This would have profound implications for designing and/or advancing personalized care for sickle cell patients and relieving disease complications.

The expanding phenotypic spectra of kidney diseases: insights from genetic studies

Next-generation sequencing (NGS) has led to the identification of previously unrecognized phenotypes associated with classic kidney disease genes. In addition to improving diagnostics for genetically heterogeneous diseases and enabling a faster rate of gene discovery, NGS has enabled an expansion and redefinition of nephrogenetic disease categories. Findings from these studies raise the question of whether disease diagnoses should be made on clinical grounds, on genetic evidence or a combination thereof. Here, we discuss the major kidney disease-associated genes and gene categories for which NGS has expanded the phenotypic spectrum. For example, COL4A3-5 genes, which are classically associated with Alport syndrome, are now understood to also be involved in the aetiology of focal segmental glomerulosclerosis. DGKE, which is associated with nephrotic syndrome, is also mutated in patients with atypical haemolytic uraemic syndrome. We examine how a shared genetic background between diverse clinical phenotypes can provide insight into the function of genes and novel links with essential pathophysiological mechanisms. In addition, we consider genetic and epigenetic factors that contribute to the observed phenotypic heterogeneity of kidney diseases and discuss the challenges in the interpretation of genetic data. Finally, we discuss the implications of the expanding phenotypic spectra associated with kidney disease genes for clinical practice, genetic counselling and personalized care, and present our recommendations for the use of NGS-based tests in routine nephrology practice.