Long-Term Follow-Up of the Human Phenotype in Three Siblings with Cone Dystrophy Associated with a Homozygous p.G461R Mutation of KCNV2

Friedburg, Christoph and Wissinger, Bernd and Schambeck, Maria and Bonin, Michael and Kohl, Susanne and Lorenz, Birgit (2011) Long-Term Follow-Up of the Human Phenotype in Three Siblings with Cone Dystrophy Associated with a Homozygous p.G461R Mutation of KCNV2. INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE, 52 (12). pp. 8621-8629. ISSN 0146-0404, 1552-5783

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Abstract

PURPOSE. To provide an up to 14-year overview of the early ocular phenotype in siblings with a homozygous p.G461R mutation in the KCNV2 gene. METHODS. Two brothers and their sister were followed-up clinically from ages 5 years, 4 years, and 2 months, respectively, including complete ophthalmological examinations. Gold-mann visual fields, two-color-threshold (2CT) perimetry, color vision testing, optical coherence tomography (OCT), fundus autofluorescence (FAF), and Ganzfeld electroretinograms (ERGs) were performed according to age-related capabilities. Genetic analyses included whole genome linkage analysis, homozygosity mapping, and candidate gene sequencing. RESULTS. All three siblings were homozygous for the p.G461R mutation. At 5 months, the younger brother had no nystagmus and Teller-acuity of 3.2 cyc/deg. At older age, all three presented nystagmus, increased light sensitivity, reduced color discrimination, and relative central scotomas. Visual acuities ranged from 20/200 to 20/70. The macula developed minor irregularities of the RPE, thinning in optical coherence tomography, and a ring of increased FAF. Scotopic (rod) sensitivity was reduced by 2 log and photopic sensitivity by 1 log in two-color-threshold perimetry. ERG responses were markedly delayed. Photopic amplitudes were severely reduced. Scotopic b-waves rose steeply with flash intensity, but for the standard flash supernormal amplitudes were only reached in the girl. CONCLUSIONS. FAF was similar to that in cone-rod dystrophy. Although cone dysfunction was accompanied by rod dysfunction, and scotopic ERGs in patient 2 deteriorated, no patient demonstrated any unequivocal sign of rod degeneration. Grossly delayed b-waves with a steep response-versus-intensity relationship rather than supernormal amplitudes should remind clinicians of this specific condition. (Invest Ophthalmol Vis Sci. 2011;52:8621-8629) DOI: 10.1167/iovs.11-8187

Item Type: Article
Uncontrolled Keywords: SUPERNORMAL ROD ELECTRORETINOGRAM; FUNDUS AUTOFLUORESCENCE; RETINAL DEGENERATION; RETINITIS-PIGMENTOSA; K+ CHANNEL; B-WAVES; GENE; ACHROMATOPSIA; DYSFUNCTION; LIGHT;
Subjects: 600 Technology > 610 Medical sciences Medicine
Divisions: Medicine > Abteilung für Pädiatrische Ophthalmologie, Strabismologie und Ophthalmogenetik
Depositing User: Dr. Gernot Deinzer
Date Deposited: 27 May 2020 08:36
Last Modified: 27 May 2020 08:36
URI: https://pred.uni-regensburg.de/id/eprint/19885

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