Genetic Interactions Between TRPC6 and NPHS1 Variants Affect Posttransplant Risk of Recurrent Focal Segmental Glomerulosclerosis. Issue 12 (3rd July 2015)

• Record Type: Journal Article
• Authors: Sun, Z. J.; Ng, K. H.; Liao, P.; Zhang, Y.; Ng, J. L.; Liu, I. D.; Tan, P. H.; Chong, S. S. C.; Chan, Y. H.; Liu, J.; Davila, S.; Heng, C. K.; Jordan, S. C.; Soong, T. W.; Yap, H. K.
• Is Part Of: American journal of transplantation. Volume 15:Issue 12(2015:Dec.)
• Page Start: 3229
• Page End: 3238
• Publication Date: 2015-07-03
• Subjects: Transplantation of organs, tissues, etc -- Periodicals; 617.95
• DOI: 10.1111/ajt.13378
• Languages: English
• ISSNs: 1600-6135

Abstract

Abstract : Individuals with TRPC6 mutations have variable phenotypes, ranging from healthy carrier to focal segmental glomerulosclerosis (FSGS) leading to renal failure. Here, we describe a family where six members had a novel TRPC6 p.R68W (c.202C>T) mutation, two of whom had renal failure from FSGS, and one had proteinuria. One healthy carrier donated a kidney to her sister. Both donor and recipient had no proteinuria at 20 years posttransplant. Two synonymous NPHS1 polymorphisms, rs2285450 (c.294C>T) and rs437168 (c.2289C>T) segregated with renal failure in this family. These variants had higher allele frequencies in 97 unrelated patients with nephrotic syndrome or FSGS compared to 224 controls. Using patch‐clamp experiments in HEK293 and podocytes, we showed that the p.R68W mutation increased TRPC6 current amplitudes, which may be explained by enhanced TRPC6 surface expression. Additionally, while wild‐type nephrin suppressed TRPC6 currents, this ability was lost in the presence of NPHS1 c.294C>T polymorphism. When cells were transfected according to combined TRPC6 and NPHS1 genotypes in the family, those representing the donor had lower TRPC6 currents than cells representing the recipient, suggesting that interactions between TRPC6 and NPHS1 variants could possibly account for the variable penetrance of TRPC6 mutations and the absence of recurrence in the graft. Abstract : The authors report the absence of focal segmental glomerulosclerosis recurrence in a live donor kidney graft transplanted 20 years previously from a sibling carrying a TRPC6 mutation, and describe functional studies to suggest that interactions between NPHS1 polymorphisms and the TRPC6 mutation may account for this lack of recurrence.