Identification of novel mutations in the GRK1 gene in an Algerian family with Oguchi disease.

Abstract

Aim: To describe novel variants in the G protein-coupled receptor kinase 1 (GRK1) gene associated with Oguchi disease and to analyze the different multimodal imaging results.

Methods: Five members of a single family were enrolled, including two confirmed cases of Oguchi disease and three carriers with novel variants in the GRK1 gene. All subjects underwent a comprehensive ophthalmological examination, including color vision testing, visual field testing, wide-field retinography, fundus autofluorescence, macular optical coherence tomography (OCT), and full-field electroretinography (ERG).

Results: The study found that both cases of Oguchi disease showed positive Mizuo-Nakamura phenomenon, moderate retinal thickening and packing of the three outermost hyper-reflective bands in the parafoveal region. After establishing a clinical diagnosis of Oguchi disease in patients IV-II and IV-III, molecular analysis revealed a similar genotype in the patients, both carrying two heterozygous variants in the GRK1 gene, the variants c.1055_1056delAC, p.(Tyr352CysfsTer32) and c.699+2T>C. Genetic testing also revealed that individual III-I was a heterozygous carrier of the novel variant c.1055_1056delAC in the GRK1 gene. In addition, the novel intronic variant c.699+2T>C was detected in the same gene in the heterozygous state in individuals III-II and IV-I. Family segregation showed that Oguchi disease was transmitted in an autosomal recessive pattern in this family.

Conclusion: Two novel variants in the GRK1 gene are reported that are linked to Oguchi disease in a naïve Algerian family. The common findings observed on the OCT scans of our affected patients include packing of the three outer hyper-reflective bands, and thickening of the retina in the parafoveal region. These features are present not only in the affected patients but also in the carriers of the disease.