Clinical and Molecular Findings in a Moroccan Family with Primary Distal Renal Tubular Acidosis and Deafness by Mutation of ATP60A4 Gene: Case Report

Abstract

Primary distal renal tubular acidosis (dRTA) is a rare genetic disease characterized by distal tubular dysfunction leading to metabolic acidosis and alkaline urine.  It is associated with impaired acid excretion by the intercalated cells in the renal collecting duct.  dRTA is developed during the first months of life and the main clinical and biologic features are failure to thrive, vomiting, dehydration, anorexia, hyperchloremic non-anion gap metabolic acidosis, hypocitraturia, hypercalciuria and nephrocalcinosis.  The disease is caused by defects in genes involved in urinary distal acidification: ATP6V0A4 and ATP6V1B1 for the recessive form, and SLC4A1 for the dominant form.  Some dRTA cases due to recessive gene mutations are associated with hearing impairment. We report the case of two siblings with dRTA, and early-onset SNHL, due to ATP6V0A4 mutations, and whose parents are heterozygous carriers of ATP6V0A4 mutations.