Tyrosinemia is an inborn error of tyrosine metabolism. There are three types of tyrosinemia (I, II and III), each has distinctive symptoms and is caused by the deficiency of a different enzyme. Tyrosinemia type II or oculocutaneous tyrosinemia is caused by a deficiency of the enzyme tyrosine amniotransferase, and is characterized by hypertyrosinemia with oculocutaneous manifestations and, in some cases, intellectual deficit. The disorder is transmitted as an autosomal recessive trait. To date, less than 150 cases have been reported in the literature. Diagnosis is based on measuring tyrosine aminotransferase (type II) activity in liver and kidney. Patients with Tyrosinemia type II usually have an isolated elevation of tyrosine only.
Patients with this type require dietary restriction of tyrosine and phenylalanine, respond to vitamin A supplementation in clearing of the skin lesions. The controlled diet results in lowering of plasma tyrosine levels and rapid resolution of the oculocutaneous manifestations. Early diagnosis of Tyrosinemia type II and protein-restricted diet are crucial to reduce the risk and the severity of long-term complications of hypertyrosinemia such as intellectual disability.