Tyrosinemia
Grace E. Kim, MD
Key Facts
Etiology/Pathogenesis
Mutations in fumarylacetoacetate hydrolase gene on 15q23-q25
Fumarylacetoacetate hydroxylase deficiency
Clinical Issues
Elevated plasma and urine succinylacetone
Many patients have renal tubular dysfunction
High risk of developing hepatocellular carcinoma
Microscopic Pathology
Pericellular and periportal fibrosis to cirrhosis
Variable fatty change and cholestasis
Top Differential Diagnoses
Galactosemia, fructosemia, and gestational alloimmune liver disease
 This micronodular cirrhotic liver demonstrates patchy areas of large droplet fatty change in some nodules. |
 A dysplastic nodule  displays both small cell change and widened plate architecture. Note the adjacent normal liver  . (Courtesy M. J. Finegold, MD.) |
TERMINOLOGY
Synonyms
Tyrosinemia, type I
Hereditary tyrosinemia
Hepatorenal tyrosinemia
Definitions
Inborn error of metabolism
Autosomal recessive inheritance
Tyrosine catabolism pathway
Deficiency of fumarylacetoacetate hydroxylase (FAH)
ETIOLOGY/PATHOGENESIS
Molecular Basis
Mutations in FAH gene on 15q23-q25
Homozygous or compound heterozygous mutations in FAH gene
FAH deficiency
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