Clinical Information

Tyrosinemia type 1 (Tyr 1) is an autosomal recessive condition caused by fumarylacetoacetate hydrolase (FAH) deficiency. Tyr 1 can cause severe liver disease, hypophosphatemic rickets, renal tubular dysfunction, and neurologic crises. If left untreated, most patients die of liver failure in the first years of life. Treatment with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3 cyclohexanedione is available and is particularly effective when initiated in newborns. The incidence of Tyr 1 is approximately 1 in 100,000 live births.

While tyrosine can be determined by routine newborn screening, it is not a specific marker for Tyr I and often may be associated with common and benign transient tyrosinemia of the newborn. Succinylacetone (SUAC) is a specific marker for Tyr I, but is not detectable by routine newborn screening. This assay determines SUAC in newborn blood spots by tandem mass spectrometry. Additional follow-up testing may include confirmatory molecular analysis of the FAH gene.