Given the predominance of MuSK autoantibodies often being well over 90% of all MuSK antibodies in patients, and the successful use of this model in previous preclinical tests of e.g., efgartigimod (an FcRn inhibitor) which is currently on the market to treat patients with MG,28,45 the use of IgG4 to model MuSK MG in mice was considered the best option for these preclinical tests. The gene discussed is MUSK; the disease is myasthenia gravis.