Clinical manifestations of enzyme deficiencies in tyrosine catabolism

Defective enzyme	Tyrosine aminotransferase	4-hydroxyphenylpyruvate dioxygenase	Homogentisate dioxygenase	Maleylacetoacetate isomerase	Fumarylacetoacetate hydrolase
Disease name(s)	Tyrosinemia type II Oculocutaneous tyrosinemia Richner-Hanhardt syndrome	Tyrosinemia type III	Alkaptonuria	No human patients described	Tyrosinemia type I Hepatorenal tyrosinemia
Elevated blood tyrosine	+++	++	∅	?	++
Corneal ulcers	+++	+/–	∅	?	∅
Hyperkeratosis	++	+/–	∅	?	∅
Intellectual disability	+/–	+/–	∅	?	∅
Arthritis	∅	∅	+++	?	∅
Liver failure	∅	∅	∅	?	+++
Renal Fanconi syndrome	∅	∅	∅	?	++

Courtesy of Markus Grompe, MD.

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