Cone dystrophy with supernormal rod responses: A rare KCNV2 gene variant

Area of Science:

• Ophthalmology
• Genetics
• Molecular Biology

Background:

• Cone dystrophy with supernormal rod responses (CDSRR) is a rare inherited retinal disorder.
• The KCNV2 gene is implicated in various retinal dystrophies.

Purpose of the Study:

• To investigate the clinical, electrophysiological, and genetic characteristics of three Portuguese families with CDSRR.
• To identify the specific KCNV2 gene variant responsible for CDSRR in these families.

Main Methods:

• Retrospective review of five patients from three families.
• Comprehensive ophthalmological examinations including multimodal imaging (FAF, SD-OCT) and electroretinography (ERG).
• KCNV2 gene mutational screening using Sanger and Next Generation Sequencing.

Main Results:

• All patients presented with childhood-onset photophobia and progressive vision loss.
• Multimodal imaging showed retinal pigment epithelium disturbances and outer retinal atrophy, worsening with age.
• A rare KCNV2 variant (p.Glu209Ter) was identified, and ERG findings were characteristic but variable.

Conclusions:

• A rare KCNV2 variant is associated with a severe, progressive retinopathy in these families.
• Significant variability in ERG responses was observed among affected individuals.
• This study expands the understanding of KCNV2-related retinopathies.