Molecular biology and molecular pathology of a newly described molecular disease--tyrosinemia II (the Richner-Hanhart syndrome).

A deficiency of hepatic tyrosine aminotransferase in humans is responsible for a syndrome of keratitis, palmar and plantar erosions and hyperkeratosis and mental retardation. Serum tyrosine increases due to the enzymatic deficiency leads to the deposition of tyrosine crystals in the eye and cornea. This deposition and possible lysosomal activation leads to inflammation in the cornea and the skin. The syndrome can be reproduced in animals who are fed a high tyrosine diet. The interaction of tyrosine crystals with membrane-bound particles can be studied in vitro with lysosomes and erythrocytes.