Distal renal
tubular acidosis (dRTA) is characterized by an inability of α-intercalated
cells in the distal nephron to secrete H+ ions into the
urine. The individual may become chronically acidotic which results in growth
retardation. The condition is also characterized by nephrocalcinosis,
hypercalciuria, and hypocitraturia. The defect in acid secretion can either be
acquired, usually seen in autoimmune conditions and drugs, or can be due to an
inherited gene defect. Mutations causing dRTA have been found in several key
transporters found in intercalated cells including the anion-exchanger 1 (AE1),
H+ATPase, and cytosolic carbonic anhydrase II1–3. Classically it was though that mutations in AE1 were inherited in
an autosomal dominant fashion and while H+ATPase in an autosomal
recessive fashion2,3. Persons with H+ATPase mutations present earlier in life
and the have a more severe phenotype than those with autosomal dominantly
inherited AE1 mutations4. Batlle has examined
previous studies looking at individuals with dRTA and found that those with the
AR form have lower serum potassium, lower serum pH, and lower bicarbonates than
their AD counterparts5. However to our knowledge no one has compared the phenotypes of the
two groups within the same center. Equally no one has previously examined the
phenotype of those with SAO and compared it with the classic AE1 mutations.