• Optic Nerve
• Genetics

Autosomal-recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) was first described among French Canadian patients from Québec presenting with a stereotypical triad of early-onset cerebellar ataxia, spastic paraplegia and peripheral neuropathy. Two recurring pathogenic mutations in the SACS gene were subsequently identified in these families in keeping with a mutational founder event in a geographically isolated population.1 However, ARSACS is being increasingly recognised worldwide as an important cause of inherited ataxia.2 Interestingly, non-Québec patients can show strikingly variable features marked by a lack of spasticity, cognitive impairment and a delayed age of onset.2 Given the heterogeneous clinical picture that can be associated with SACS mutations, the identification of ancillary features linked with these genetic defects could prove particularly useful in prioritising the most appropriate lines of investigations when confronted with a suspected case of ARSACS. Although prominent retinal hypermyelination is thought to be a characteristic manifestation of classical ARSACS among Québec patients, this ophthalmological finding has only been described infrequently in patients from Europe, Asia and the Middle East.2 A recent case report has even further argued that retinal ‘hypermyelination’ in ARSACS is a pathologically misleading term that should be …