NBCe1A is encoded by a member of the solute carrier family SLC4A4. Mutations in SLC4A4 cause severe proximal renal tubular acidosis (pRTA), with a plasma pH of 7.04–7.27 and a plasma bicarbonate concentration of 3–17 mmol/L. This evidence concerns the gene SLC4A4 and proximal renal tubular acidosis.