OCA2 and oculocutaneous albinism: p.R305W was predominantly identified in index cases of OCA (9 patients with p.R305W versus 4 patients with p.R419Q of 21 patients carrying two mutant OCA2 alleles) and p.R419Q was predominantly identified in OA3 index cases (4 patients with p.R419Q versus 2 patients with p.R305W of 14 patients carrying two mutant OCA2 alleles).