Myasthenia gravis (MG) is an autoimmune disorder with fluctuating weakness in the skeletal muscles, caused by specific autoantibodies targeting the acetylcholine receptor (AChR), or less frequently against the muscle specific kinase (MuSK) or the low-density lipoprotein receptor-related protein 4 (LRP4) at the neuromuscular junction [16,17]. The gene discussed is MUSK; the disease is myasthenia gravis.