CHRNA4 and myasthenia gravis: In MG, anti-nAChR antibodies reduce the number of AChRs at the endplate resulting in decrease sensitivity to acetylcholine (ACh), impairment of sodium (Na+) channels and increased threshold depolarization needed to trigger an action potential (AP), ultimately decreasing the safety factor (SF) for neuromuscular transmission (Ruff and Lennon, 2008).