Identification of novel mutations in the ortholog of Drosophila eyes shut gene (EYS) causing autosomal recessive retinitis pigmentosa

Abstract

Purpose: Recently, a novel gene was cloned for autosomal recessive retinitis pigmentosa (arRP), EYS, on 6q12. This study was conducted to determine the spectrum and frequency of EYS mutations in 195 unrelated patients with autosomal recessive and autosomal dominant RP (adRP).

Methods: All cases had a complete ophthalmic examination, and the clinical diagnosis of RP was based on visual acuity, fundus photography, and electroretinography findings. The DNA extracted from all participants was subjected to molecular genetic analysis entailing amplification of the coding regions and exon-intron boundaries of EYS by polymerase chain reaction, followed by direct sequencing. Bioinformatics analysis was undertaken to study the effect of the identified mutations on protein structure and function.

Results: Eleven novel missense, nonsense, and splice site mutations were identified within EYS in 10 unrelated arRP patients, with probable allele frequency of 11%. However, no mutations were observed in the adRP panel. In addition, 53 single-nucleotide polymorphisms (SNPs) were found, of which 12 were previously unreported. Bioinformatics analyses revealed that all mutations were highly conserved across other species and/or involved important domains on protein structure. Intrafamilial phenotypic variability was also observed in a family with double heterozygous mutations.

Conclusions: This is the first report of molecular genetic analysis of EYS in a cohort of unrelated British and Chinese patients with RP. The results further the initial hypothesis that EYS is a major causative gene for recessive RP and emphasize the role of different types of mutations in disrupting the function of EYS.