Abstract:

Objective: To summarize the clinical, electrophysiological and genetic characteristics of a pedigree with myotonic dystrophy (DM). Methods and Results: The 25-year-old male proband exhibited an occult onset, characterized by a distinctive "hatchet face" and alopecia, limb muscle weakness, amyotrophy, and damages of various systems, including the endocrine system and heart damage. Notably, the third aunt, the fourth uncle and the first brother of proband also exhibited similar clinical symptoms. Gene detection revealed both the proband, his aunt and his cousin had CTG repeats exceeding 100 times in the DMPK gene. Electromyography (EMG) studies conducted on the proband, his aunt and his cousin showed the coexistence of myotonic potential and myogenic damage. In the proband, the amplitude of the motor nerve conduction velocity of the left common peroneal nerve was decreased with a slight reduction in velocity, while the sensory nerve conduction velocity was also slowed. The proband, his aunt and his cousin were diagnosed with myotonic dystrophy type 1 (MD1). It was evident that the pedigree has myotonic dystrophy. Conclusions: Myotonic dystrophy is a rare autosomal dominant inheritance disorder characterized by myasthenia, myotonia and amyotrophy, which affects multiple systems. The clinical manifestations of this disease are diverse and relatively uncommon. In clinical practice, it is crucial to pay attention to the patient's family history, clinical signs and electrophysiological data, with particular emphasis on the identification of myotonic potential. Gene detection is of great significance for the diagnosis and differential diagnosis of myotonic dystrophy.

Key words: Myotonic dystrophy, Trinucleotide repeat expansion, Electromyography, Neural conduction, Genetic testing, Pedigree

摘要：

目的: 报道强直性肌营养不良一家系的临床表现、电生理学特点和基因检测结果，总结疾病的临床和遗传学特征。方法与结果: 先证者为男性，25岁，隐匿发病，临床表现为“斧状脸”的特殊面容和秃发，四肢无力、肌萎缩，伴多系统如内分泌系统和心脏损害；家族中三姑、四叔和大表弟有类似临床症状。基因检测，先证者及其三姑、大表弟DMPK基因CTG序列重复次数> 100次。针极肌电图检查，先证者及其三姑、大表弟均表现为肌强直电位和肌源性损害共存，先证者左侧腓总神经运动传导速度稍减慢且波幅降低、感觉神经传导速度减慢。先证者及其三姑、大表弟确诊为强直性肌营养不良1型，该家系明确为强直性肌营养不良家系。结论: 强直性肌营养不良是一组以肌无力、肌强直和肌萎缩为特点的累及多系统的常染色体显性遗传性疾病，临床表现复杂多样且较为罕见，应注意家族史、临床体征和电生理检测结果尤其是肌强直电位的识别，基因检测对疾病的诊断与鉴别诊断具有重要意义。

关键词: 营养不良性肌强直, 三核苷酸重复扩增, 肌电描记术, 神经传导, 基因检测, 系谱