RÉSUMÉ
The clinical data of 3 cases with myasthenia in Children′s Hospital of Fudan University were retrospectively analyzed.All the 3 patients were diagnosed with myasthenia gravis and given pyridostigmine bromide, but the treatment effect was unsatisfactory.One patient had left lower limb weakness and motor development impairment, and was diagnosed with centronuclear myopathy by gene testing.One patient had blepharoptosis, accompanied by developmental delay, facial deformity, and toe deformity.This patient was diagnosed with chromosome 18p syndrome by chromosome analysis.One patient had weakness of both legs, slight development retardation, and significantly high lactic acid levels.Basal nuclei lesions were observed under head magnetic resonance imaging (MRI). Whole exome sequencing (WES) and mitochondrial genome testing results revealed Leigh syndrome.Through summing up experience and lessons, strengthen and improve the clinical identification ability of clinicians for myasthenia gravis, and avoid misdiagnosis.