TYR and oculocutaneous albinism: Comparison of individuals with two pathogenic TYR sequence variants with individuals who are compound heterozygous for the haplotype GYGQ and a pathogenic TYR sequence variant, shows a more severe phenotype in the former group (35 of the 37 had a clinical diagnosis of OCA compared to 15 out of 21 in the latter group; the remaining six has a clinical diagnosis of OA or AROA).