强直性肌营养不良基因CTG数与心电图关系

Electrocardiographic findings in myotonic dystrophy are correlated with the number of CTG repeats

目的 研究强直性肌营养不良 (DM)的肌张力蛋白激酶 (MT -PK)基因中三核苷酸CTG(胞嘧啶、胸腺嘧啶、鸟嘌呤 )重复数与DM病人心电图变化的关系。方法 用PCR扩增及地高辛杂交法对 5例临床诊断DM病人及其中 2个家系的 1 5名成员进行MT -PK基因 3′端非编码区CTG重复数检测 ,经DM基因诊断DM病人 1 6例 ,正常人 4例 ,在检测基因时均作心电图检查。结果 1 6例DM病人心电图异常率 81 .2 5 % (1 3例 ) ,明显高于 4例正常人的心电图异常率 2 5 % (1例 ) ,1 3例DM病人心电图异常主要表现为心脏传导障碍 ,而且心电图异常与其神经症状严重程度及与DM基因CTG重复数有关 ,病情重者 ,CTG数高者其心电图变化明显。

Objective To study the relevance of CTG(cytosine thymidine guanine) repeat expansion of MT PK gene and cardiac involvment in myotonic dystrophy. Method CTG repeats of MT PK gene in 5 cases diagnosed clinically as DM and their 15 family numbers were studied by PCR and Southen blot. According to the number of CTG repeats of MT PK gene (range 30 to >1609, normally≤37), 16 patients were DM and 4 was normal individuals. Electrocardiogram (ECG) in both DM patients and normal individuals was taken during DNA analysis. Results The rate of abnormal ECG was higher in 16 DM patients (13 cases, 81.25%) than that in 4 normal individuals (1 only, 25%). ECG in 13 DM patients showed mainly cardiac conduction abnormalities. Abnormals ECGs of the 13 patients were correlated with the severity of neurologic symptoms and number of CTG repeats of MT PK gene. Severe illness with more CTG repeats had obvious ECG changes. Conclusion The number of CTG repeats can predict cardiac involvement in DM. (Shanghai Med J, 2000,23∶592 595)