The Slc4a4-null animal, corresponding to the one used in the present studies, and the Slc4a4W516X/W516X avatar mouse engineered to mimic a non-sense mutation found in a human patient, are affected by severe metabolic acidosis due to proximal renal tubular acidosis (pRTA; Gawenis et al., 2007; Lo et al., 2011). The gene discussed is SLC4A4; the disease is proximal renal tubular acidosis.