Genotypes & Phenotypes in Belgian Patients with Albinism.

Purpose To study the different genotypes and phenotypes in Belgian patients with albinism. Methods Phenotypes and genotypes in a cohort of 89 patients were studied in detail. These patients were then grouped according to genotype. Results A total of 40 patients with isolated oculocutaneous ( OCA), and 11 with XL ocular albinism ( XLOA) were molecularly confirmed. Nine syndromic OCA patients were identified. Genotypes of 29 patients were unknown at the time of study. Although not statistically significant due to small sample size, patients with a proper TYR mutation in combination with a temperature sensitive variant ( TS) generally showed milder characteristics. A study of one specific family showed 3 affected siblings with this genotype. However, 2 normal children, each of a different patient, also had this genotype. There was perfect concordance between fundoscopic identification of lyonization in 15 female carriers of XLOA, and molecular confirmation of heterozygosity. Two adult patients with Chediak-Higashi syndrome showed OCA in combination with neurodegeneration. Systemic abnormalities in 7 Hermansky-Pudlak syndrome patients were very variable. Conclusions Molecular analysis is essential to confirm clinical phenotyping in albinism. A causal relationship between a combination of a TYR mutation and the TS variant is as yet uncertain and requires more in depth analysis. [ABSTRACT FROM AUTHOR]