The apolipoprotein L gene family maps to a region on chromosome 22 and encodes six highly homologous proteins designated apoL-I, apoL-II, apoL-III, apoL-IV, apoL-V and apoL-VI, all of which function as components of plasma lipoproteins. ApoL-IV (apolipoprotein L-IV), also known as APOL4, is a 351 amino acid protein that exists as multiple alternatively spliced isoforms, one of which is secreted. Expressed in spleen, placenta, spinal cord, uterus, testis and trachea, apoL-IV is thought to play a role in lipid exchange and transport throughout the body and may be involved in reverse cholesterol transport, specifically from peripheral cells to the liver. Overexpression of apoL-IV is associated with schizophrenia, suggesting that apoL-IV may play a role in the pathogenesis of neural disorders.