Abstract
Purpose::
To study the phenotypic spectrum of prevalent mutations in the Israeli albino population.
Methods::
Phenotypic evaluation included description of hair, eye and skin color, presence of nevi and ability to tan. Eye examination included visual acuity, presence of nystagmus, transillumination, visibility of choroidal vessels and hypoplasia of the macula. Genetic investigation included ethnic origin and detailed pedigree analysis of the extended families. DNA was extracted from blood samples and analyzed by PCR followed by restriction enzyme digestion or by sequencing.
Results::
We have screened over 300 Israeli albinos, mainly Jewish and Arab, for mutations in the TYR and P genes, and correlated the frequent mutations in homozygous and compound heterozygous states, with their detailed phenotypes. The mutations can be divided into "severe" and "mild" mutations according to the clinical manifestations. The severe TYR gene mutations (M1V, G47D, S50X, R217FS, G253R, E294K, T373K, R402X, IVS2-1G>A) in homozygous or compound heterozygous state, cause the severe phenotype namely OCA IA. Mild TYR mutations in homozygous or compound heterozygous states with mild or severe mutations, usually cause milder phenotypes with inter- and intrafamilial variability. Surprisingly, inter- and intrafamilial variability was also observed in homozygotes for the missense P gene mutation G27R, and the range of phenotypes overlapped those observed in albinos homozygotes for the mild TYR gene mutation IVS2-7T>A. Homozygotes for the very mild TYR gene mutation, R217W, have never been detected.
Conclusions::
In groups of albinos sharing the same genotypes and ethnic origins, as compared to previously published individual results, the spectrum of clinical manifestations can be determined. The accumulated data are important for the prediction of the range of severity of clinical manifestations in newborns and very young children with specific genotypes prevalent in our population.
Keywords: gene/expression • low vision • mutations