Tyrosinemia type II is characterized by corneal dystrophy, painful palmoplantar hyperkeratosis, and variable intellectual disability. Individuals diagnosed and treated from early infancy may be asymptomatic or have only mild ocular and skin manifestations. Individuals with delayed diagnosis or lack of treatment present with ocular, skin, and variable cognitive manifestations.

Tyrosinemia type III (TYRSN3), an autosomal recessive disorder caused by a deficiency in the activity of 4-hydroxyphenylpyruvate dioxygenase (HPD), is characterized by elevated levels of blood tyrosine and massive excretion of its derivatives into urine. Patients with this disorder have mildly impaired intellectual development and/or convulsions, with the absence of liver damage (summary by Tomoeda et al., 2000).

Hawkinsinuria (HWKS) is an autosomal dominant inborn error of metabolism. Metabolic acidosis and tyrosinemia are transient, and symptoms improve within the first year of life. Patients continue to excrete the hawkinsin metabolite in their urine throughout life (Danks et al., 1975; Tomoeda et al., 2000).

Any mitochondrial DNA depletion syndrome in which the cause of the disease is a mutation in the TFAM gene.