Kidney Week 2025 Annual Meeting-Genetic Insights into Tubular Function: Unlocking the Mysteries of Chronic Electrolyte Disorders

Video Transcription

Video Summary

The symposium focused on how genetic discoveries in renal tubules explain chronic electrolyte disorders and guide care. Jim McCormick reviewed regulation of the thiazide-sensitive sodium–chloride cotransporter (NCC) in the distal convoluted tubule (DCT), contrasting Gitelman syndrome (loss-of-function SLC12A3; low/normal BP, hypokalemic alkalosis, hypomagnesemia, hypocalciuria) with familial hyperkalemic hypertension (FHHT; high NCC activity; hypertension, hyperkalemic acidosis). He outlined the WNK4→SPAK pathway as the main in vivo activator of NCC and showed how KLHL3/CUL3 ubiquitin ligase normally degrades WNK4; FHHT mutations impair this, increasing NCC activity. CUL3 “Δ9” mutations act through self-degradation plus excessive KLHL3 degradation. He also discussed EAST/SESAME syndrome (KCNJ10/Kir4.1) and the “DCT potassium switch,” linking serum potassium to WNK4/NCC activity and explaining why high dietary potassium can lower blood pressure.<br /><br />Todd Alexander presented renal magnesium handling. In the DCT, Mg enters via TRPM6/7 and is regulated by factors like EGF; multiple genetic defects (TRPM6, CNNM2, ATPase subunits, HNF1B/17q12 deletion) cause Mg wasting. In the thick ascending limb, Mg reabsorption is largely paracellular through claudin-16/19, blocked by claudin-14; mutations cause FHHNC, while claudin-10 defects cause HELIX syndrome with hypermagnesemia. Experiments suggested the Ca-sensing receptor strongly affects calciuria via claudin-14 but has limited effect on magnesuria at physiologic Mg levels. Proximal tubule data supported claudin-2 conferring preferential calcium over magnesium permeability, potentially preventing papillary calcium precipitation.<br /><br />Orson Moe discussed kidney stones as a systemic, genetically influenced disease with both monogenic and polygenic contributions, highlighting TRPV5/6 variants affecting calcium transport. Mallory Downey connected tubular genetics to diagnosis and management, emphasizing careful phenotyping, targeted genetic testing, and future potential for gene-editing therapies.

Asset Subtitle

Moderator(s): Gerardo Gamba, Jennifer Pluznick

Presentation(s):

Spectrum of Sodium Chloride Cotransporter Regulation: From Gitelman to Gordon Syndromes - James McCormick
Magnesium Wasting: A Window into Tubular Magnesium Handling - R. Todd Alexander
Stone Formers and Genetic Links: Calcium Channels Under the Spotlight - Orson Moe
From Bench to Bedside: Translating Tubular Genetics into Clinical Care - Mallory Downie

Meta Tag

Date 11/6/2025

Pathway 1 Genetic Diseases and Development

Session ID 506830

Keywords

renal tubule genetics

chronic electrolyte disorders

NCC (SLC12A3)

distal convoluted tubule (DCT)

Gitelman syndrome

familial hyperkalemic hypertension (FHHT)

WNK4-SPAK pathway

KLHL3/CUL3 ubiquitin ligase

CUL3 Δ9 mutation

DCT potassium switch

TRPM6/TRPM7 magnesium transport

claudin-16/claudin-19 (FHHNC)

claudin-14 regulation

kidney stones genetics

TRPV5/TRPV6 calcium transport variants