pediatrics
Tyrosine Metabolism Disorders
Tyrosinemia type II
This rare Autosomal Recessive disorder is caused by tyrosine transaminase deficiency. Accumulation of tyrosine causes cutaneous and corneal ulcers. Secondary elevation of phenylalanine, though mild, may cause neuropsychiatric abnormalities if not treated. Diagnosis of tyrosinemia type II is by elevation of tyrosine in plasma, absence of succinylacetone in plasma or urine, and genetic testing; measurement of decreased enzyme activity in liver biopsy is usually not needed. This disorder is easily treated with mild to moderate restriction of dietary phenylalanine and tyrosine. 