What is familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC)?

Updated: Oct 30, 2020
  • Author: Tibor Fulop, MD, PhD, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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In FHHNC, an autosomal-recessive disorder, profound renal magnesium and calcium wasting occurs. The hypercalciuria often leads to nephrocalcinosis, resulting in progressive renal failure. [17, 19, 76] Other symptoms that have been reported in patients with FHHNC include urinary tract infections, nephrolithiasis, incomplete distal tubular acidosis, and ocular abnormalities. [99]

FHHNC is caused by mutations in the gene CLDN16, which encodes for paracellin-1 (claudin-16), [18] a member of the claudin family of tight junction proteins that form the paracellular pathway for calcium and magnesium reabsorption in the TAL. FHHNC with ophthalmologic disease indicates potential claudin-19 mutation. [100, 101, 102]

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