Proximal renal tubular acidosis-ocular anomaly syndrome (PRTAO) is a rare autosomal recessive systemic disease resulting from isolated impairment of bicarbonate (HCO3-) reabsorption in the proximal renal tubules, which is characterized by a decreased renal HCO3- threshold. Affected individuals exhibit stunted growth and eye anomalies, including band keratopathy, cataracts, and glaucoma. Affected individuals may also exhibit impaired intellectual development and dental defects (Igarashi et al., 2001; Inatomi et al., 2004; Dinour et al., 2004).