LRP4 and myasthenia gravis: Myasthenia gravis (MG) is an autoimmune disease in which antibodies bind to acetylcholine receptors (AChR) or to other functional molecules, such as muscle-specific kinase (MuSK) and lipoprotein-receptor-related protein 4 (LRP4), in the postsynaptic membrane at the neuromuscular junction (NMJ) (1).