The renal tubular acidosis (RTA) syndromes are a group of disorders characterized by an inability to excrete acid that is out of proportion to any reduction in glomerular filtration rate, and results from tubular defects in urinary acidification involving either the distal nephron (distal RTA) or the proximal nephron (proximal RTA). Distal renal tubular acidosis is characterized by an elevation in urinary pH despite the presence of serum acidosis. Complete distal tubular renal acidosis is responsible for delayed growth, plasma acidosis with hyperchloremia, hypokalemia, and hypercalciuria with nephrocalcinosis and hypocitruria. dRTA shows both autosomal recessive and autosomal dominant patterns of inheritance. Patients with recessive dRTA may also present with osteopetrosis, deafness, and mental retardation. Treatment includes administration of potassium and sodium bicarbonate supplements, in order to bring bicarbonate, potassium, and calcium levels within acceptable limits, and also to boost growth and reduce the calciuria.
Fawaz et al. (2012) described seven children (two males and five females) with familial distal renal tubular acidosis (dRTA) in association with membrane defect hemolytic anemia. All children were born to consanguineous parents (there were a female-female and a male-female siblings). The children presented with hyperchloremic normal anion gap metabolic acidosis, failure to thrive, and mild to moderate compensated anemia with striking red cell morphology with acanthocytosis and echinocytosis. Splenomegaly was detected in two patients; five patients had rickets; nephrocalcinosis was found in three patients; one patient had hydronephrosis; one patient had mild bilateral conductive deafness; and one patient suffered from epileptic fits. All patients were found to carry a single homozygous mutation in the SLC4A1 gene.