They encompass autoantibodies against nicotinic receptor for acetylcholine (AchR) in 80% of cases, against muscle-specific kinase (MuSK) in 10% of cases (often more severe MG), against lipoprotein-related protein 4 (LPR4) in 1–3% of cases (less severe MG. This evidence concerns the gene MUSK and myasthenia gravis.