SLC4A1 gene is part of the anion-exchanger (AE) family. The gene encodes two AE1 isoforms (also called band 3): erythroid (eAE1) and renal (rAE1). These isoforms are expressed in the erythrocyte plasma membrane, which function as chloride/bicarbonate exchanger involved in carbon dioxide transport from tissues to lungs. The eAE1 isoform is a glycoprotein consisting of 911 amino acids and has three domains: the N-terminal cytoplasmic domain (containing the binding sites for hemoglobin and some cytosolic enzymes), which acts as a membrane anchorage site for the red cell skeleton, the transmembrane domain, which is responsible for Cl-/HCO3- exchange; and a short cytoplasmic C-terminal domain, containing binding sites for carbonic anhydrase II. The rAE1 isoform is transcribed from the second promoter in intron 3, and lacks the first 65 amino acids of the N-terminal domain. Defects in this protein are the cause of an autosomal recessive disease called Renal Tubular Acidosis, Distal, with Hemolytic Anemia (dRTA-HA), characterized by the association of hemolytic anemia with distal renal tubular acidosis, variable hyperchloremic hypokalemic metabolic acidosis, nephrocalcinosis, and nephrolithiasis, caused by reducing the ability to acidify urine.