DNA diagnosis of congenital myotonic dystrophy

应用基因特异性探针p5B1.4进行Southern杂交，分析了55例强直性肌营养不良(DM)患者的CTG重复扩增情况，其中包括25例先天性DM患者。在糖尿病患者中，CTG重复序列在从父母传播到儿童严重程度时被扩大。DM家族表现出遗传预期，疾病严重程度增加，发病年龄更早，代代相传。先天性糖尿病的传播被认为是纯母体传播。我们在分子分析的基础上提出了第一例由无症状父亲传播的先天性糖尿病患者。通过对一例先天性糖尿病患者不同组织中CTG重复序列的分析，揭示了先天性DM患者存在躯体不稳定性，并分析了先天性DM患者骨骼肌和淋巴细胞DNA CTG重复序列的大小。在所有患者中，来自骨骼肌的DM-PK的大小比来自淋巴细胞的增加了约1.5kb到3.5kb。DM-PK存在于神经肌肉接头、肌梭和肌肉活检的肌膜。在培养的肌肉中，DM-PK表达于成肌细胞和肌管的胞浆中。

We have analyzed CTG repeat expansion in 55 myotonic dystrophy (DM) patients, including 25 congenital DM by Southern hybridization using DM gene specific probe (p5B1.4). The CTG repeat was expanded in DM patients when transmitted from parent to child severity. DM families showed genetic anticipation, an increase in disease severity and earlier age of onset in successive generations. The transmission of congenital DM was considered exclusively maternal. We present the first congenital DM patients transmitted from asymptomatic father on the basis of molecular analysis. Based on analysis of CTG repeat in various tissues from a patient of congenital DM,the presence of somatic instability was disclosed.We have analyzed the size of the CTG repeat of DNAs extracted from skeletal muscle and lymphocytes in congenital DM patients. The size from skeletal muscle showed an increase of about 1.5kb to 3.5kb larger than that from lymphocytes in all patients.We present expression of DM-PK on biopsied muscles and cultured muscles by immunocytochemistry using antibody aganist synthetic DM-PK peptide antigen. DM-PK was observed in neuromuscular junctions, muscle spindle, and sarcolemma on biopsied muscles. On cultured muscles, DM-PK was expressed in cytoplasma of myoblast and myotube.