Lysinuric Protein Intolerance

Lysinuric protein intolerance (LPI) is a genetic condition that is caused by the body's inability to digest the amino acids lysine, arginine, and ornithine. These are some of the building blocks of protein. Because the body cannot effectively break down these amino acids, which are found in many protein-rich foods, individuals experience nausea and vomiting after ingesting protein. Symptoms usually develop after infants are weaned and begin to eat solid foods. Without treatment, other signs and symptoms associated with protein intolerance may also occur, including short stature, muscle weakness, impaired immune function, and weak brittle bones (osteoporosis). The most serious symptoms involve the lung, kidney and heart. A lung disorder called pulmonary alveolar proteinosis may develop in some individuals, as can end-stage renal disease, coma and intellectual disability.

Lysinuric protein intolerance is caused by mutations in the SLC7A7 gene and is inherited in an autosomal recessive manner.  It is diagnosed based on the symptoms, laboratory and genetic testing. This condition is treated with a modified diet and medications. The long-term outlook depends on the age that LPI is diagnosed and the response to treatment.