Tyrosinemia type III

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Tyrosinemia type III
Classification and external resources
Specialty endocrinology
ICD-10 E70.2
ICD-9-CM 270.2
OMIM 276710
DiseasesDB 29836
eMedicine ped/2339
MeSH D020176

Type III tyrosinemia is a rare disorder caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase (EC, encoded by the gene HPD. This enzyme is abundant in the liver, and smaller amounts are found in the kidneys. It is one of a series of enzymes needed to break down tyrosine. Specifically, 4-hydroxyphenylpyruvate dioxygenase converts a tyrosine byproduct called 4-hydroxyphenylpyruvate to homogentisic acid. Characteristic features of type III tyrosinemia include mild mental retardation, seizures, and periodic loss of balance and coordination (intermittent ataxia). Type III tyrosinemia is very rare; only a few cases have been reported.

Pathophysiology of metabolic disorders of tyrosine, resulting in elevated levels of tyrosine in blood.