Isolated rod dysfunction associated with a novel genotype of CNGB1

• Published in: American journal of ophthalmology case reports Vol. 14; pp. 83 - 86
• Main Authors: Ba-Abbad, Rola, Holder, Graham E, Robson, Anthony G, Neveu, Magella M, Waseem, Naushin, Arno, Gavin, Webster, Andrew R
• Format: Journal Article
• Language: English
• Published: United States Elsevier 01.06.2019
• Subjects: Case Report; Night blindness; Rod dysfunction; Cyclic nucleotide-gated channels; Retinitis pigmentosa; Cone-isolated retina; Glutamic-acid rich protein (GARP)
• ISSN: 2451-9936; 2451-9936
• DOI: 10.1016/j.ajoc.2019.03.004

To describe the clinical and electrophysiological features of an unusual retinopathy in a patient with a novel genotype of , mutations in which are implicated in autosomal recessive retinitis pigmentosa (rod-cone dystrophy). A 61-year old asymptomatic woman was referred to the inherited retinal disorders clinic because of peripheral retinal pigmentary changes. She had normal visual acuity and color vision. Clinical examination and detailed imaging of the macula were normal, but there was atrophy of the outer retina in the periphery with sparse intra-retinal pigmentation. Electroretinography (ERG) revealed undetectable rod responses, with normal cone-mediated responses. The pattern ERG was normal. Genetic analysis identified two previously unreported variants in : (c.2258T > A, p.[Leu753*] and c.807G > C, p.[Gln269His]), shown to be . This report describes a functionally cone-isolated retina in an adult, apparently hemizygous for a novel missense mutation in , a novel phenotype for this gene. The p.[Gln269His] allele is the first missense change, within the glutamic acid-rich protein (GARP) domain of CNGB1, to be associated with retinal disease in humans.