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

ABSTRACT

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.

KEYWORDS:

• Arylsulfatase G
• ARSG
• Usher syndrome
• Usher syndrome type 4
• USH4
• atypical Usher syndrome
• retinitis pigmentosa
• RP

Acknowledgments

The authors would like to acknowledge the Foundation Fighting Blindness My Retina Tracker Registry Genetic Testing Study for supporting genetic counseling for rare inherited retinal diseases.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This work was supported in part by the National Institutes of Health (NIH) under award number R01DC019054 [to C.W.V.K]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported in part by the Foundation Fighting Blindness My Retina Tracker Registry Genetic Testing Study.