MUSK and myasthenia gravis: Myasthenia gravis (MG) is a chronic, immune-related neuromuscular disease with presence of autoantibodies against nicotinic acetylocholine receptors (AChR), muscle-specific kinase (MuSK) autoantibodies to low-density lipoprotein receptor-related protein 4 (Lpr4) or remains seronegative [69,70].