Patients with MG who are seropositive for autoantibodies to the acetylcholine receptor (AChR), muscle-specific tyrosine kinase (MuSK), or low-density lipoprotein receptor-related protein 4 (LRP4) present with voluntary muscle weakness due to dysfunctional neuromuscular junctions and impaired neuromuscular transmission (1, 2). The gene discussed is MUSK; the disease is myasthenia gravis.