IGHG3 and myasthenia gravis: In patients with myasthenia gravis, the majority (80 to 85%) have anti-acetylcholine receptor (AChR) antibodies (IgG1 and IgG3) [54,55], while the remainder have autoantibodies that target other components of the neuromuscular junction, such as anti-muscle-specific kinase IgG4 and anti-lipoprotein-receptor related protein 4 IgG1 or IgG3 [56,57].