tyrosinemia type I

Full Definition

An autosomal recessive disorder caused by deficiency of fumarylacetoacetate hydrolase, the final enzyme in tyrosine catabolism. This leads to accumulation of toxic metabolites including succinylacetone, which can cause severe liver dysfunction, renal tubular defects, and increased risk of hepatocellular carcinoma. Newborn screening detects elevated tyrosine levels, though succinylacetone is a more specific marker. Treatment with NTBC (nitisinone) can prevent most complications if started early. Without treatment, the condition is often fatal in the first year of life.

Usage

Usage note: Always specify 'type I' to distinguish from other forms of tyrosinemia.

In Context

• "Succinylacetone measurement confirmed tyrosinemia type I despite only mildly elevated tyrosine." — Diagnostic laboratory report
• "Early NTBC therapy in tyrosinemia type I prevents hepatic complications and improves long-term outcomes." — Treatment guideline