About Muscle-Specific Kinase Myasthenia Gravis (MuSK MG)
MG is an autoimmune disease caused by autoantibodies targeting parts of the neuromuscular junction, leading to motor impairment, shortness of breath, disabling fatigue, and episodes of respiratory failure. Generalized MG, or gMG, affects approximately 50,000 to 80,000 patients in the United States.
gMG can be classified into two primary types:
- AChR MG – B cells produce autoantibodies against the acetylcholine receptor (AChR). Patients are typically treated with acetylcholinesterase inhibitors.
- MuSK MG – B cells produce autoantibodies against MuSK, a transmembrane protein on the surface of the muscle membrane. These patients typically do not respond to acetylcholinesterase inhibitors and are treated with corticosteroids, generalized immunosuppressants, and in cases of severe disease, intravenous immunoglobulin and rituximab. However, these methods are associated with relapse and often, ongoing dependence on corticosteroids.
- 50,000 to 80,000 patients in the U.S. are affected by generalized MG (gMG).
- ~6% to 7.5% of patients with gMG have autoantibodies against MuSK.
- ~85% of patients with gMG have autoantibodies against AChR.