CD63 and amyotrophic lateral sclerosis: In vivo, ALS patient muscle biopsies presented an increased frequency of multi‐vesicular bodies (MVBs) (0.017 MVBs/sarcomere in ALS muscles, vs. 0.004 MVBs/sarcomere in healthy controls; FigureS1C,D), an accumulation of extracellular vesicle markers at the periphery of the myofibres (Figure1E,F), and an increased expression level of the vesicle marker CD63 (Figure1G,H).