Lysinuric protein intolerance (LPI) is a rare autosomal recessive disorder of AA transport caused by mutations in the SLC7A7 gene, coding for the y+L amino acid transporter 1 (y+LAT1), which transfers cationic AAs Orn, Arg, and Lys from the cell to the extracellular space. The gene discussed is PSMB6; the disease is lysinuric protein intolerance.