Lysinuric Protein Intolerance

Gene : SLC7A7

What is lysinuric protein intolerance?

Lysinuric protein intolerance (LPI) is an inherited disorder that affects the body's ability to utilize certain building blocks of proteins. This condition usually appears after an infant is weaned and receives greater amount of protein from solid foods. Affected infants may have recurrent vomiting and diarrhea, nausea after a protein-rich meal, poor feeding, aversion to protein-rich food, enlarged liver and spleen, and muscular weakness. Overtime they may develop problems such as short stature, brittle bones, dysfunction of the lungs, impaired immune system , and kidney disease, which may be life threatening. LPI may lead to elevated ammonia levels in the blood, which may cause coma and intellectual disability. Treatment of LPI involves long term restriction of protein in diet and administration of arginine chloride and nitrogen scavenger drugs. LPI is caused by pathogenic variants in the SLC7A7 gene.

How is lysinuric protein intolerance inherited?

LPI is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for LPI. However, the risk to have a child affected with LPI is increased. Testing of reproductive partners is recommended for carriers of LPI.

How common is lysinuric protein intolerance?

LPI is found worldwide, but the exact occurrence is unknown. However, it is more common in some populations, where it is estimated to occur in 1 in 60,000 newborns in Finland and 1 in 57,000 newborns in Japan.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems







GI Tract


Carrier Rates
Detection Rate
Carrier Frequency
Finnish > 99% 1 in 123
General Population 80% 1 in 121

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