KCNV2-Associated Retinopathy: Genetics, Electrophysiology, and Clinical Course—KCNV2 Study Group Report 1

Michalis Georgiou, Anthony G. Robson, Kaoru Fujinami, Shaun M. Leo, Ajoy Vincent, Fadi Nasser, Thales Antônio Cabral De Guimarães, Samer Khateb, Nikolas Pontikos, Yu Fujinami-Yokokawa, Xiao Liu, Kazushige Tsunoda, Takaaki Hayashi, Mauricio E. Vargas, Alberta A.H.J. Thiadens, Emanuel R. de Carvalho, Xuan Thanh An Nguyen, Gavin Arno, Omar A. Mahroo, Maria Inmaculada Martin-MeridaBelen Jimenez-Rolando, Gema Gordo, Ester Carreño, Ayuso Carmen, Dror Sharon, Susanne Kohl, Rachel M. Huckfeldt, Bernd Wissinger, Camiel J.F. Boon, Eyal Banin, Mark E. Pennesi, Arif O. Khan, Andrew R. Webster, Eberhart Zrenner, Elise Héon, Michel Michaelides

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Purpose: To investigate genetics, electrophysiology, and clinical course of KCNV2-associated retinopathy in a cohort of children and adults. Study design: This was a multicenter international clinical cohort study. Methods: Review of clinical notes and molecular genetic testing. Full-field electroretinography (ERG) recordings, incorporating the international standards, were reviewed and quantified and compared with age and recordings from control subjects. Results: In total, 230 disease-associated alleles were identified from 117 patients, corresponding to 75 different KCNV2 variants, with 28 being novel. The mean age of onset was 3.9 years old. All patients were symptomatic before 12 years of age (range, 0-11 years). Decreased visual acuity was present in all patients, and 4 other symptoms were common: reduced color vision (78.6%), photophobia (53.5%), nyctalopia (43.6%), and nystagmus (38.6%). After a mean follow-up of 8.4 years, the mean best-corrected visual acuity (BCVA ± SD) decreased from 0.81 ± 0.27 to 0.90 ± 0.31 logarithm of minimal angle of resolution. Full-field ERGs showed pathognomonic waveform features. Quantitative assessment revealed a wide range of ERG amplitudes and peak times, with a mean rate of age-associated reduction indistinguishable from the control group. Mean amplitude reductions for the dark-adapted 0.01 ERG, dark-adapted 10 ERG a-wave, and LA 3.0 30 Hz and LA3 ERG b-waves were 55%, 21%, 48%, and 74%, respectively compared with control values. Peak times showed stability across 6 decades. Conclusion: In KCNV2-associated retinopathy, full-field ERGs are diagnostic and consistent with largely stable peripheral retinal dysfunction. Report 1 highlights the severity of the clinical phenotype and established a large cohort of patients, emphasizing the unmet need for trials of novel therapeutics.

Original languageEnglish (US)
Pages (from-to)95-107
Number of pages13
JournalAmerican journal of ophthalmology
Volume225
DOIs
StatePublished - May 2021

ASJC Scopus subject areas

  • Ophthalmology

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