Late presented congenital myasthenic syndrome with novel compound heterozygous CHRNE mutations mimicking seronegative myasthenia gravis

We found a late presented congenital myasthenic syndrome (CMS) patient with novel CHRNE gene mutations. Although our patient has shown blepharoptosis since youth, fatigable muscle weakness began at age 71. Genetic analysis revealed novel compound heterozygous CHRNE mutations (c.1032+2T>G, c.1306_1307 delGA). His myasthenic symptoms were well managed by oral anti‐cholinesterase drug until he died at 82‐year‐old. The present case showed mild myasthenic symptoms with very late presentation and slow progression. Late presented CMS is often underdiagnosed; therefore, genetic testing is important to distinguish it from other myasthenic disease.