OCA3 E70.3

The cause is a mutation in the TYRP1 gene. This gene encodes a melanosomal enzyme that belongs to the tyrosinase family and plays an important role in the melanin biosynthesis pathway.

Clinically, there is a rather inconspicuous phenotype with red-brown hair. Mild ocular symptoms are detectable.

The encoded protein plays a role in melanin biosynthesis (Kenny EE et al.2012). Catalyzes the oxidation of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) to indole-5,6-quinone-2-carboxylic acid in the presence of bound Cu(2+) ions, but not in the presence of Zn(2+) (Lai X et al. (2017). May regulate or influence the type of melanin synthesized. To a lesser extent, it is also able to hydroxylate tyrosine and produce melanin.

1. Kenny EE et al.(2012)Melanesian blond hair is caused by an amino acid change in TYRP1. Science 336:554.
2. Lai X et al. (2017) Structure of Human Tyrosinase Related Protein 1 Reveals a Binuclear Zinc Active Site Important for Melanogenesis. Angew Chem Int Ed Engl 56: 9812-9815.