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. 2025 Sep 15:1-8.
doi: 10.1080/13816810.2025.2554660. Online ahead of print.

Multimodal imaging and electrophysiological features in bradyopsia associated with homozygous variants (c.895T>C) in Regulator of G-protein Signaling 9 (RGS9)

Grace A Borchert  1   2   3   4 , Rachael C Heath Jeffery  1   5 , Sian Sperring  4 , Morag Shanks  4   6 , Jennifer Whitfield  4   6 , Penny Clouston  4   6 , Tina Lamey  7 , Jennifer A Thompson  7 , Danial Roshandel  1 , Enid S Chelva  7 , Charles Cottriall  4 , Kanmin Xue  3   4   8 , Samantha R De Silva  3   4 , Jasmina Cehajic-Kapetanovic  3   4 , Robert E MacLaren  3   4 , Terri McLaren  1   7 , Andrea H Nemeth  3   9 , Susan M Downes  3   4 , Fred K Chen  1   2   5
Affiliations

Multimodal imaging and electrophysiological features in bradyopsia associated with homozygous variants (c.895T>C) in Regulator of G-protein Signaling 9 (RGS9)

Grace A Borchert et al. Ophthalmic Genet. .

Abstract

Purpose: To report multimodal imaging findings and natural history of clinical features in two probands with bradyopsia harboring homozygous variants (c.895T>C) in Regulator of G-protein Signaling 9 (RGS9).

Methods: Ophthalmic history, clinical examination, fundus autofluorescence (FAF), optical coherence tomography (OCT), microperimetry, flood-illuminated adaptive optics (AO) imaging, and electroretinogram (ERG) were obtained.

Results: A 37-year-old male and a 67-year-old female from non-consanguineous parents had normal fundus examination, FAF, and OCT. ERGs for the male case between the age of 4 and 38 years showed no progression. Both probands had flat International Society for Clinical Electrophysiology of Vision (ISCEV) Standard full-field ERG light-adapted (LA) responses but dark-adapted (DA) red x-wave and S-cone responses were present. DA 30 Hz flicker was present after 2 but not after 10 seconds. The reduced amplitude and b:a ratio of the DA10 response improved with increasing interstimulus interval. AO and microperimetry demonstrated preservation of foveal cone density and subnormal retinal sensitivity, respectively. Both measures remained stable over 3 years. The c.895T>C variant was classified as pathogenic.

Conclusions: Bradyopsia associated with homozygous RGS9 c.895T>C variants is characterized by normal retinal structure but subnormal macular sensitivity. Extended ERG protocols can be used to confirm delayed phototransduction recovery.

Keywords: Cone dysfunction syndrome; adaptive optics; electroretinography; microperimetry; prolonged electro-retinal response suppression (PERRS).

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