MG is a rare chronic neuromuscular autoimmune disease caused by antibodies against the acetylcholine receptor (AChR) or, more rarely, against muscle-specific kinase (anti-MuSK Ab) or lipoprotein-related protein 4 (LRP-4) or triple-seronegative (triple-SN) MG, in which all these antibodies are absent [52,57,58,59]. Here, LRP4 is linked to myasthenia gravis.