<unk>  is a rare disorder caused by a deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase (), 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<unk> <unk> <unk>  include mild mental retardation, seizures, and periodic loss of balance and coordination (intermittent ataxia).<unk> <unk> <unk>  is very rare; only a few cases have been reported. Pathophysiology of metabolic disorders of tyrosine, resulting in elevated levels of tyrosine in blood.
Tyrosinemia type III
Hawkinsinuria
Aspartylglucosaminuria
Aldolase A deficiency
Phenylketonuria
Transaldolase deficiency
Argininemia
Essential fructosuria