Chorea is a pleiotropic clinical feature of mutated fused-in-sarcoma in amyotrophic lateral sclerosis

Around 10% of all amyotrophic lateral sclerosis (ALS) cases are familial and around 3–5% are fused-in-sarcoma (FUS)-related in Europe. We report a 43-year-old patient with a pathogenic FUS mutation (c.1561C>G p.(Arg521Gly) who presented at our clinic with chorea and subsequently with progressive symptoms of classical ALS. As a result of progressive upper and lower motor neurone deterioration, chorea disappeared and death occurred 2.5 years after the onset of the first manifestations. This first description adds chorea as a possible pleiotropic clinical feature in FUS-related ALS. It further warrants to systematically ask and check for chorea in ALS patients and their relatives.