In addition to the hypomineralized enamel phenotype, patients with mutations in SLC4A4 have corneal opacities (band keratopathy), cataracts, glaucoma, severe proximal renal tubular acidosis, calcification of the basal ganglia, elevated serum amylase and lipase, and mental retardation [10], [11], [12]. Here, SLC4A4 is linked to proximal renal tubular acidosis.