重症肌无力是一种神经肌肉接头间传递功能障碍的慢性病。其特征是受累的横纹肌运动后容易疲劳,经休息或用抗胆碱脂酶类药物后症状可减轻或消失。胸腺对重症肌无力发病起到重要作用,有人报告大约75％的重症肌无力病例可有胸腺异常,其中三分之一左右为胸腺肿瘤,余为胸腺肥大,但在小儿较为少见。本文报道4例患重症肌无力同胞兄妹,其中3例 Myasthenia gravis is a chronic disease that transmits dysfunction between neuromuscular junctions. It is characterized by involvement of striated muscle movement fatigue, after taking a rest or with anti-cholinergic drugs can reduce or eliminate the symptoms. Thymus plays an important role in the pathogenesis of myasthenia gravis. It has been reported that about 75% of patients with myasthenia gravis may have thymus abnormalities, of which about one-third are thymoma and more than thymus hypertrophy, but rare in children. This article reports 4 cases of myasthenia gravis siblings, of which 3 cases