强直性肌营养不良1型患者的临床特点及CTG重复次数分析

The clinical characteristics and number of CTG repeats in patients with myotonic dystrophy type 1: An analysis of 3 cases

摘要:

目的 总结强直性肌营养不良1型患者的临床、神经电生理和遗传学特点。方法 收集3例强直性肌营养不良1型患者的临床症状、肌电图、肌肉病理及基因检测结果。结果 3例患者（男性1例）均为成年起病，慢性病程。临床表现为四肢远端无力和肌强直；2例患者存在眼外肌或面肌无力；1例伴随前额脱发；2例存在心脏传导紊乱如阵发性室性心动过速、左前束支传导阻滞、右束支传导阻滞；2例出现脑白质病变。3例强直性肌营养不良1型患者DMPK基因3'非翻译区的突变CTG重复次数分别为104、150、299，均大于50次。3例患者肌电图检查所检肌肉均可见肌强直放电。结论 强直性肌营养不良1型患者肌无力主要出现在远端肌群，心脏传导紊乱和脑白质病变是其多系统受累的显著表现。肌电图可以发现临床下肌强直放电，是最敏感的筛查手段。

Abstract:

Objective To summarize the clinical, neuroelectrophysiological, and genetic characteristics in patients with myotonic dystrophy type 1 (MD1). Methods The clinical symptoms and the results of electromyographic, myopathological, and genetic tests were collected from three patients with MD1. Results All the three patients (1 male) experienced an onset at adult age with a chronic disease course and presented with myotonia and muscle weakness in distal limbs; two patients had extraocular muscle or facial muscle weakness; one patient had concomitant forehead alopecia; two patients had cardiac conduction disorders such as paroxysmal ventricular tachycardia, left anterior bundle branch block, and right bundle branch block; two patients had white matter lesions. The number of CTG repeats in the 3'-untranslated region of the DMPK gene were 104, 150, and 299, respectively, in the three patients with MD1, all of which were bigger than 50. The electromyographic tests of all the three patients showed tonic discharges of muscles. Conclusions Patients with MD1 show muscle weakness mainly in distal muscle groups with cardiac conduction disorders and white matter lesions as their prominent manifestations of multiple system involvement. Electromyography can detect tonic discharges of muscles in clinical practice, which makes it the most sensitive screening method for the disease.