Distal renal tubular acidosis (
dRTA) or RTA type I is characterised by reduced H+
hydrogen ions and
ammonium urinary excretion. In children affected by
dRTA there is
stunted growth,
vomiting,
constipation, loss of appetite,
polydipsia and
polyuria,
nephrocalcinosis, weakness and muscle
paralysis due to hypokalaemia. This work summarises progress made in
dRTA genetic studies in populations studied so far.
DRTA is heterogeneous and as such, transporters and
ion channels are analysed which have been identified in alpha-intercalated cells of the collecting duct, which could explain cases of
dRTA not associated with the hitherto studied genes.
DRTA can be autosomal dominant or autosomal recessive. Autosomal recessive
dRTA appears in the first months of life and progresses with
nephrocalcinosis and early or late
hearing loss. Autosomal dominant
dRTA is less severe and appears during adolescence or adulthood and may or may not develop
nephrocalcinosis. In alpha-intercalated cells of the collecting duct, the
acid load is deposited into the urine as titratable
acids (
phosphates) and
ammonium. Autosomal recessive
dRTA is associated with mutations in genes ATP6V1B1, ATP6V0A4 and SLC4A1, which encode subunits a4 and B1 of V-
ATPase and the AE1
bicarbonate/
chloride exchanger respectively. By contrast, autosomal dominant
dRTA is only related to mutations in AE1.