Neurophysiological and ophthalmological findings of SPG7-related spastic ataxia: a phenotype study in an Irish cohort

Background Mutations in SPG7 are increasingly identified as a common cause of spastic ataxia. We describe a cohort of Irish patients with recessive SPG7- associated phenotype. Methods Comprehensive phenotyping was performed with documentation of clinical, neurophysiological, optical coherence tomography (OCT) and genetic data from individuals with SPG7 attending two academic neurology units in Dublin, including the National Ataxia Clinic. Results Thirty-two symptomatic individuals from 25 families were identified. Mean age at onset was 39.1 years (range 12–61), mean disease duration 17.8 years (range 5–45), mean disease severity as quantified with the scale for the assessment and rating of ataxia 9/40 (range 3–29). All individuals displayed variable ataxia and spasticity within a spastic-ataxic phenotype, and additional ocular abnormalities. Two had spasmodic dysphonia and three had colour vision deficiency. Brain imaging consistently revealed cerebellar atrophy ( n = 29); neurophysiology demonstrated a length-dependent large-fibre axonal neuropathy in 2/27 studied. The commonest variant was c.1529C > T (p.Ala510Val), present in 21 families. Five novel variants were identified. No significant thinning of average retinal nerve fibre layer (RNFL) was demonstrated on OCT ( p = 0.61), but temporal quadrant reduction was evident compared to controls ( p