Multimodal imaging and genetic findings in a case of ARSG-related atypical Usher syndrome

Background: Atypical Usher syndrome has recently been associated with arylsulfatase G (ARSG) variants. In these cases, characteristic findings include progressive sensorineural hearing loss (SNHL) without vestibular involvement and ring-shaped late-onset retinitis pigmentosa (RP).Materials and Methods: One patient with atypical Usher syndrome and a novel homozygous ARSG variant was included in this study. The patient underwent a comprehensive ophthalmic examination, including multimodal imaging and genetic testing.Results: A 60-year-old male of Persian decent presented to our clinic with a history of 20 years of progressive SNHL, and 10 years of progressive peripheral vision loss and pigmentary retinopathy. Consistent with previous reports of ARSG-related atypical Usher syndrome, fundus examination revealed ring-shaped retinal hyperpigmentation and fundus autofluorescence (FAF) demonstrated a six-zone pattern of autofluorescence. Optical coherence tomography (OCT) showed extensive cystoid spaces concentrated in the ganglion cell layer. Widefield OCT angiography at the level of the choriocapillaris showed signs of atrophy that corresponded to the FAF hypofluorescent zone. The patient was homozygous for a novel ARSG variant c. 1270 C > T, p. Arg424Cys.Conclusion: We report a novel ARSG variant in a case of atypical Usher syndrome and describe multimodal imaging findings that further characterize the effect of ARSG in the pathogenesis of atypical Usher syndrome.