Coexistence of Autosomal Dominant Polycystic Kidney Disease and Hereditary Distal Renal Tubular Acidosis in a Child: A Very Rare Case Report and Literature Review

Coexistence of ADPCKD and dRTA

Abstract

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited cystic kidney disease that exhibits a variety of clinical manifestations due to multiple mutation types and a variety of penetration powers.

Renal tubular acidosis (RTA) is a group of transport defects secondary to reduced proximal tubular reabsorption of bicarbonate (HCO3-), the distal secretion of protons (hydrogen ion, H+), or both, resulting in impaired capacity for net acid excretion and persistent hyperchloremic metabolic acidosis with a normal anion gap (AG) 12±2 mmol/L. The above conditions are either secondary to other causes or primary, with or without known genetic defects.

ADPKD rarely can cause RTA, however, the potential heritage interactions of ADPKD and distal renal tubular acidosis (dRTA) mutations have not yet been identified. As far as we know, dRTA and ADPKD have not been reported in the same patient. Here we present a 4-year-old patient who was diagnosed with ADPKD with PKD1 (NM_001009944.3): c.11014C>T (p.Arg3672Trp) heterozygous and type1 RTA (dRTA) with SLC4A1 (NM_00342.4): c.1765C>T (p.Arg589Cys) heterozygous mutation, but no sign of cystic kidney disease in his mother despite having the same PKD1 mutation. Although his father has incomplete dRTA (metabolic acidosis was absent, however urinary pH was 7 and history of recurrent kidney stones.) having the same SLC4A1 mutation. The child is being treated with 5–8 mEq/kg of citrate, and cyst growth seems to have stopped following a 2-year follow-up. The case highlights the importance of "secondary hits" or the coexistence of different abnormalities in the development of cystic formation in ADPKD.