This nuclear gene encodes a mitochondrial protein tyrosine aminotransferase which is present in the liver and catalyzes the conversion of L-tyrosine into p-hydroxyphenylpyruvate. Mutations in this gene cause tyrosinemia (type II, Richner-Hanhart syndrome), a disorder accompanied by major skin and corneal lesions, with possible mental retardation. A regulator gene for tyrosine aminotransferase is X-linked.