Rod-sparing in a bardet-biedl syndrome patient with mutations in the ARL6 gene

• Published in: Documenta ophthalmologica 2024-10, Vol.149 (2), p.133-138
• Main Authors: Pincay, Jorge, Rodriguez, Marilyn, Kaushal, Divya, Tsang, Stephen H.
• Format: Article
• Language: English
• Subjects: ARL6 gene; Bardet-Biedl syndrome; Clinical Case Report; Color vision; Dystrophy; Hereditary diseases; Medicine; Medicine & Public Health; Mutation; Ophthalmology; Phenotypes; Pleiotropy; Polydactyly
• ISSN: 0012-4486; 1573-2622; 1573-2622
• DOI: 10.1007/s10633-024-09985-8

Purpose Bardet-Biedl Syndrome (BBS) is an autosomal recessive disorder characterized by pleiotropism that affects multiple organ systems. The primary features of BBS include rod-cone dystrophy, renal anomalies, post axial polydactyly, and neurologic deficits. The clinical picture of BBS is extensively heterogenous, with inter and intra familial patients varying in levels of syndromic manifestations and severity of symptoms. Methods In this study we examined a monocular BBS patient who was compound heterozygous for mutations in the ARL6 (BBS3) gene. Results The patient reported visual complaints consistent with a clinical picture of cone or cone-rod dystrophy. Fundus imaging showed retinal mottling on color photos and a parafoveal hyperfluorescent ring on short wave autofluorescence (SW-AF). Full field electroretinogram (ffERG) revealed normal scotopic step tracings and diminished amplitudes in the photopic steps. Conclusion This rod-sparing result was consistent with cone-dystrophy and is the first known case of a rod-sparing ffERG phenotype in a BBS patient with mutations in the ARL6 gene. This contributes to the existing phenotype and may potentially contribute to furthering our understanding of BBS pathophysiology.