Majority of MG patients (around 80–85%) develop Abs against the acetylcholine receptors (AChR; AChR MG), whereas muscle-specific kinase Abs (MuSK; MuSK MG) are detected in 1–10% patients, depending on detection techniques used and the differences between the source population (5, 8, 9). The gene discussed is MUSK; the disease is myasthenia gravis.