In the proximal tubule, mutations of solute carrier 4A4 (SLC4A4) (electrogenic Na<sup>+</sup>/HCO<sub>3</sub><sup>-</sup>-cotransporter Na<sup>+</sup>/bicarbonate cotransporter e1 [NBCe1]) and other genes such as CLCN5 (Cl<sup>-</sup>/H<sup>+</sup>-antiporter), SLC2A2 (GLUT2 glucose transporter), or EHHADH (enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase) causing more generalized proximal tubule dysfunction can cause proximal renal tubular acidosis resulting from bicarbonate wasting and reduced ammoniagenesis.