Spastic Paraplegia Type 7-Associated Optic Neuropathy: A Case Series

Abstract

Background: Hereditary optic neuropathies comprise a group of clinically and genetically heterogeneous disorders. Optic neuropathy has been previously reported in families with spastic paraplegia type 7 (SPG7) gene mutations. However, the typical time course and clinical presentation of SPG7-associated optic neuropathy is poorly understood. We report a series of 5 patients harboring pathogenic SPG7 mutations who originally presented to a neuro-ophthalmology clinic with symptoms of optic neuropathy. Methods: Retrospective case series of 5 patients with pathogenic SPG7 mutations and optic atrophy from 3 neuro-ophthalmology clinics. Demographic, clinical, diagnostic, and treatment data were collected and reported by the clinician authors. Results: Five patients ranging in age from 8 to 48 years were evaluated in the neuro-ophthalmology clinic. Although there were variable clinical presentations for each subject, all noted progressive vision loss, typically bilateral, and several also had previous diagnoses of peripheral neuropathy (e.g., Guillain-Barré Syndrome). Patients underwent neuro-ophthalmic examinations and testing with visual fields and optic coherence tomography of the retinal nerve fiber layer. Genetic testing revealed pathogenic variants in the SPG7 gene. Conclusions: Five patients presented to the neuro-ophthalmology clinic with progressive vision loss and were diagnosed with optic atrophy. Although each patient harbored an SPG7 mutation, this cohort was phenotypically and genotypically heterogeneous. Three patients carried the Ala510Val variant. The patients demonstrated varying degrees of visual acuity and visual field loss, although evaluations were completed during different stages of disease progression. Four patients had a previous diagnosis of peripheral neuropathy. This raises the prospect that a single pathogenic variant of SPG7 may be associated with peripheral neuropathy in addition to optic neuropathy. These results support the consideration of SPG7 testing in patients with high suspicion for genetic optic neuropathy, as manifested by symmetric papillomacular bundle damage without clear etiology on initial workup. Applied judiciously, genetic testing, including for SPG7, may help clarify the cause of unexplained progressive optic neuropathies.