A novel variant in the G-protein receptor kinase (GRK1) causes Oguchi syndrome, type II, in an Egyptian family.

PURPOSE: This study aimed to report the clinical, electrophysiological, and genetic findings in two siblings of an Egyptian family with type 2 Oguchi disease, with multimodal imaging performed for proper evaluation.

METHODS

Two siblings of consanguineous parents presented with poor night vision underwent full ophthalmological examination, ultra-widefield fundus photography, fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (SD-OCT) of the macula, repeated fundus photography following dark adaptation for 3 hours and electroretinogram (ERG). Exome sequencing (ES) was performed for one patient and Sanger sequencing was then used for segregation analysis.

RESULTS

The clinical findings and investigations were suggestive of the Oguchi disease phenotype. The ES revealed a homozygous stop gain variant, first time to be detected in Ouchi II patient, in exon 6 of the G-protein receptor kinase 1 (GRK1) gene, c.1338c>A: p.Cys446Ter.

CONCLUSIONS

These are the first molecularly confirmed patients from Egypt with Oguchi disease type 2. In addition, we identified a pathogenic GRK1 variant first time to be detected in Oguchi II patients expanding both the phenotypic and mutational spectrum of Oguchi disease.