Funding sources: MGH receives financial support from the LUMC (OIO, 2017), Top Sector Life Sciences & Health to Samenwerkende Gezondheidsfondsen via the Target to B! consortium (LSHM18055-SGF), Prinses Beatrix Spierfonds (W.OR-17.13 and W.OR-19.13) and the Dutch Science Organization NWO (VENI 0915016181 0040). MGH and JJP are members of the Netherlands Neuromuscular Center and the European Reference Network for rare neuromuscular diseases EURO-NMD. MGH and JJP are coinventors on two patent applications on MuSK-related research. LUMC, MGH, JJP receive license income from these patents. LUMC receives royalties for a diagnostic MuSK ELISA. RLP receives financial support from the "Association Française contre les Myopathies" (AFM). WDP received financial support from the Lambert Initiative for Cannabinoid Therapeutics and Bridging Grants from The University of Sydney (no grant numbers available). Funders had no role in the writing of this review.