Myasthenia gravis (MG), the most frequent autoimmunity of the neuromuscular junction, with a prevalence of 150–200 cases per million [1], is a postsynaptic disease caused by autoantibodies directed most frequently against the acetylcholine receptor (RAch) in up to 90% of the generalized cases and against the muscle-specific receptor tyrosine kinase (MuSK) in 1–10% of cases [1,2,3]. The gene discussed is MUSK; the disease is myasthenia gravis.