Chapter 19 - Disorder: Lysinuric protein intolerance

Abstract

Lysinuric Protein Intolerance (LPI, OMIM # 222700) is caused by a defective transporter protein at the basolateral membrane of kidney and intestinal epithelial cells that does not allow transport of the dibasic / cationic amino acids, lysine, ornithine and arginine. This transporter is also expressed in hepatic cells, pulmonary epithelial cells and alveolar macrophages. Metabolic abnormalities seen result from deficient absorption, reabsorption and transport of the dibasic amino acids. In LPI, the dibasic amino acids are not absorbed into the blood through the intestinal epithelial cells and are not reabsorbed from the ultrafiltrate in the renal tubule cells. This results in a shortage of lysine, ornithine and arginine in the body, with diminished concentrations in the blood, and excess amounts of these three amino acids being excreted into the urine.