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Abstract: SA-OR45

CLVS1 H310Y Is a Novel Cause of Familial Childhood Steroid-Sensitive Nephrotic Syndrome

Session Information

Category: Pediatric Nephrology

  • 1700 Pediatric Nephrology

Authors

  • Lane, Brandon M., Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, United States
  • Chryst-Stangl, Megan, Duke Molecular Physiology Institute, Durham, North Carolina, United States
  • Wu, Guanghong, Duke Molecular Physiology Institute, Durham, North Carolina, United States
  • Shalaby, Mohamed Ahmed, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
  • El desoky, Sherif Mohamed, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
  • Kari, Jameela Abdulaziz, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
  • Gbadegesin, Rasheed A., Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, United States
Background

Nephrotic syndrome (NS) is the most common glomerular disease seen in children. It is estimated that up to 30% of steroid resistant NS (SRNS) may be due to mutations in one of sixty genes reported in cohort of patients with familial or idiopathic SRNS. However, the genetic causes of the more common steroid sensitive NS (SSNS) and the molecular basis for variability in glucocorticoid response have remained elusive. Our overarching hypothesis is that single gene causes of SSNS can be identified in cohorts of sibling pairs with SSNS and identification of such genes can provide insight into the molecular basis of glucocorticoid response.

Methods

To identify single gene causes of SSNS in a cohort of patients with familial SSNS and examine the molecular basis of glucocorticoid response, we carried out whole genome sequencing in forty families with hereditary SSNS. After identifying a potential disease-causing variant, we examined the effects of loss of gene function in cultured human podocytes through the creation of lentiviral shRNA knockdown and CRISPR- Cas9 knockout cell lines as well as morpholino-based gene knockdown in zebrafish.

Results

We identified a rare homozygous variant, CLVS1 H310Y, that segregates with disease in a consanguineous family with two affected siblings and a cousin. CLVS1 encodes clavesin1, a component of clatherin mediated endocytosis. This variant was not present in a homozygous state in >200,000 chromosomes and is predicted to be pathogenic by in silico analyses. Morpholino knockdown of the orthologous CLVS1 gene in zebrafish resulted in edema phenotypes indicative of loss of glomerular filtration barrier (GFB) integrity. This edema phenotype could be rescued with wildtype human CLVS1 mRNA but not the H310Y variant. Knockdown of CLVS1 in cultured human podocytes as well as overexpression of the H310Y variant in HEK 293 cells decreased endocytosis of fluorescently labeled dextran and increased susceptibility to apoptosis. These aberrant podocyte phenotypes could be rescued in the presence of glucocorticoid, mimicking the steroid responsive phenotype in patients bearing the CLVS1 H310Y variant.

Conclusion

We identified a mutation in CLVS1 as a new cause of hereditary SSNS. Our data demonstrates the requirement of functional CLVS1 in the maintenance of podocyte viability and GFB integrity.

Funding

  • NIDDK Support