强直性肌营养不良患者及家系成员基因的三核苷酸重复数检测

Analysis of CTG repeat number of myotonic dystrophy (DM) gene in DM patients and their family members

探讨强直性肌营养不良（ＤＭ）患者及家系成员三核苷酸重复数ＣＴＧ（胞嘧啶、胸腺嘧啶、鸟嘌呤）的变化。方法用聚合酶链反应（ＰＣＲ）扩增及ＤＮＡ杂交法对５例临床诊断ＤＭ患者及其中３个家系的其他１１名成员和１名正常人进行了ＤＭ基因的ＣＴＧ重复数的测定。结果１名正常人ＣＴＧ三核苷酸重复数是３０个，５例ＤＭ病人均在８５个以上，其中２例在１６０５个以上，明显高于正常人ＣＴＧ重复数，而且ＣＴＧ重复数与临床症状轻重有关。１１名家系成员中除２名正常外，余９例ＣＴＧ拷贝数均超过正常范围，此９例据此诊断为ＤＭ。结论ＤＭ基因诊断与其临床诊断相一致，而且该基因诊断可早期发现ＤＭ家系中无临床症状的ＤＭ患者，也可对临床可疑的ＤＭ患者进行鉴别诊断。

Objective To study the change of CTG repeat numbers in patients and family mumbers of DM. Method CTG repeat numbers of DM gene from 5 patients diagnosed as DM clinically, their 11 family members and a healthy subject were analysed by polymerase chain reaction and Southern blot. Resutls The numbers of CTG repeat were 30 in one normal individual, and it ranged from 85 to >1 609 in 5 patients with DM which were higher than the normal person. The numbers of CTG repeats in 9 of 11 family members were higher than the normal value, these 9 persons were diagnosed as DM depending on the expansion of CTG repeat, and remaining 2 cases were normal ones. The severity degree of clinical symptoms of these 5 patients was related to degree of amplification of CTG. Conclusion The gene diagnosis of DM is consistent with its clinical diagnosis. The non symptom cases of DM can be found earlier with gene diagnosis which is useful for differentiating persons suspected DM disease clinically.