Inflammatory masquerade features in adult-onset CLN-associated retinal degeneration in a multiethnic Asian cohort

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Abstract Purpose To describe the clinical, imaging, and genetic features of non-syndromic neuronal ceroid lipofuscinosis (NCL)-associated retinal degeneration in a multi-ethnic Asian cohort, with particular emphasis on cases that were initially considered in the differential diagnosis of non-neoplastic uveitis masquerade syndromes. Methods This retrospective case series reviewed seven unrelated Singaporean patients (Chinese and Indian ancestry) with genetically confirmed CLN-associated inherited retinal degeneration. Clinical presentation, inflammatory features, longitudinal multimodal imaging, electrophysiology, and molecular findings were analyzed. Results Symptom onset ranged from 18 to 54 years. Presenting symptoms included “blurred vision/floaters (n = 3)”, “nyctalopia (n = 3)”, and “hemeralopia (n = 1)”. Five patients presented with active ocular inflammation, such as vitreous cells and retinal vasculitis. Notably, the other two patients (harboring CLN2 and CLN3 variants) did not show overt anterior or posterior segment inflammation; however, their striking structural and imaging similarities to inflammatory retinopathies prompted their inclusion in the masquerade differential. Across all seven patients, serial optical coherence tomography (OCT) revealed relentless outer retinal atrophy and loss of the ellipsoid zone. One of the five patients received corticosteroid and immunosuppressive therapy but showed only a limited response, whereas the remaining four patients responded favourably to topical, periocular, or oral corticosteroids. During a follow-up of 2.7–33.1 years, median best-corrected visual acuity declined to logMAR 1.90. Systemic health remained stable without neurological symptoms, except for one CLN2- associated case developing adult-onset neurosensory hearing loss. Genetic testing showed pathogenic variants were identified in CLN1 -, CLN2- , CLN3- , CLN5- , and CLN7- . CLN-associated disease represented 1.1% of the inherited retinal disease families assessed. Conclusions Retinal degeneration associated with CLN1 , CLN5 , and CLN7 variants frequently presented with intraocular inflammation (ranging from anterior to panuveitis) in our cohort. Yet even patients without obvious inflammatory signs experienced a relentless retinal decline that closely mimicked the structural damage seen in severe posterior uveitis. These findings highlight why early genetic testing is so crucial when working up atypical, symmetrical posterior uveitis or suspected masquerade syndromes.