[Novel autoantibodies in myasthenia gravis]

Patients with myasthenia gravis(MG) are divided into three groups: (1) acetylcholine receptor antibody positive MG: 80%, (2) muscle-specific receptor tyrosine kinase (MuSK) antibody positive MG: 5-10%, and (3) double seronegative MG. In 2011, autoantibodies (Abs) against low-density lipoprotein receptor-related protein 4(Lrp4) were identified in Japanese MG patients and thereafter have been reported in Germany and USA. In other Lrp4 Ab papers, Lrp4 Ab positive sera inhibited agrin-induced aggregation of AChRs in cultured myotubes, suggesting a pathogenic role regarding the dysfunction of the neuromuscular endplate. Anti-MuSK autoantibodies were revealed to block binding of collagen Q (ColQ) to MuSK. Anti-Kv1.4 antibodies targeting alpha-subunits(Kv1.4) of the voltage-gated potassium channel occurs frequently among MG patients with thymoma. Further understandings of neuromuscular junction structure and functions through newly discovered autoantibodies may provide more specific clinical information and treatments in MG.