Tyrosinemia III

Introduction
Autosomal recessive due to deficiency of 4-hydroxyphenylpyruvate dioxygenase in the
liver and kidney, typically affected individuals suffer from neurological deficits and mental
retardation.

Clinical Features
Unclear clinical spectrum, eye problems as in Tyrosinemia type II may occur
Consequences
Remain unclear at this time

Diagnosis
Newborn screen
Tandem mass spectrometry
Confirmation
Diagnosis is by enzyme assay in liver or kidney biopsy specimens. Plasma tyrosine
  levels are typically 500-1200 µmol/l

Treatment
A low protein or special diet restricting phenylalanine and tyrosine will alleviate symptoms
 and may be protective against pathology including neurological sequelae. Aim for
 tyrosine levels below 500µmol/l.

Situations that risk metabolic decompensation

Monitoring
Plasma tyrosine level
Urinary organic acids
Ophthalmic follow up to avoid ulceration.

STAT emergency treatment

Infection/Immunization

Surgical/surgical procedures

Growth and development
As these patients are maintained on a restricted diet it is crucial to closely monitor all
growth parameters on a regular basis. In cases with neurological deficits the child should
be integrated into an early intervention program and developmental progress closely
monitored by both the metabolic team and the primary care provider. It is hoped that pre-
symptomatic identification and treatment of patients with Tyrosinemia type III will
prevent any long-term problems.

Figure