Tyrosinemia type I is a rare, inherited metabolic condition in which the body cannot fully break down tyrosine, an amino acid found in protein. Toxic byproducts build up and can damage the liver and kidneys and raise the risk of liver cancer. It is screened for at birth because early treatment prevents these serious complications.
What causes tyrosinemia type I
The condition is caused by variants in the FAH gene, which provides instructions for an enzyme needed in the final step of breaking down tyrosine. When the enzyme is missing, harmful intermediate compounds accumulate. Tyrosinemia type I is inherited in an autosomal recessive pattern, so a child inherits one variant from each parent.
How newborn screening detects it
Newborn screening looks for a marker called succinylacetone in the blood spot from the heel prick, which is a specific and reliable indicator of tyrosinemia type I. An abnormal result prompts confirmatory blood and urine testing and gene analysis.
How tyrosinemia type I is treated
Treatment combines a medication called nitisinone, which blocks the buildup of toxic byproducts, with a carefully managed low-tyrosine and low-phenylalanine diet, often using a special medical formula. Started early and maintained over time, this approach protects the liver and kidneys and allows healthy development.
How genetic screening fits in
State newborn screening does an excellent job of catching tyrosinemia type I. Genetic screening looks at the same picture from the DNA level and, in a single test, can also assess the genes tied to more than 1,000 other clinically actionable childhood conditions, many of which are not on any state panel. Fore Genomics offers an at-home cheek-swab screen, sequenced in CLIA-certified and CAP-accredited labs, with results supported by board-certified genetic counselors. See what we screen for or start screening.
Frequently asked questions
Is tyrosinemia on newborn screening panels?
Yes. Tyrosinemia type I is a core condition on the federal Recommended Uniform Screening Panel and is screened for across U.S. states.
Can it be managed?
Yes. With nitisinone and dietary management started early, most children do well. Care is guided by a metabolic specialist.
Is it inherited?
Yes. Tyrosinemia type I is autosomal recessive, so a child inherits an FAH variant from each parent.
Related guides
- Newborn Screening Guide (all conditions and states)
- PKU (Phenylketonuria)
- Maple Syrup Urine Disease (MSUD)
Medically reviewed by Fore's Clinical Team. This article is for general educational purposes and is not medical advice. Sources: HRSA Newborn Screening; National Organization for Rare Disorders (NORD).