不同表型肌营养不良症患者抗肌营养不良蛋白基因缺失类型的研究

目的探讨我国东北地区杜氏型肌营养不良症（DMD）及贝克型肌营养不良症（BMD）患者抗肌营养不良蛋白基因缺失类型分布与表型的关系,并用于产前基因诊断。方法采用多重PCR法检测124例来自东北地区的DMD（106例）及BMD（18例）男性患者的抗肌营养不良蛋白基因缺失情况,并对30例高危胎儿行产前抗肌营养不良蛋白基因缺失检测。结果124例患者中,抗肌营养不良蛋白基因缺失检出率为49％（61／124）,其中41例（41／61,67％）缺失分布于外显子45—53,13例（13／61,21％）缺失分布于外显子8—19,5例（5／61,8％）在上述两个外显子缺失区内均有缺失,2例（2／61,3％）缺失分布于外显子34和43;缺失型患者中有9例发生整码缺失（为BMD患者）,49例发生移码突变（为DMD患者）。30例高危胎儿中,17例为男性胎儿,其中10例为抗肌营养不良蛋白基因缺失型,缺失位点与先证者相同;13例为女性胎儿,无一例抗肌营养不良蛋白基因缺失。结论DMD及BMD患者抗肌营养不良蛋白基因缺失主要分布于两个区域,外显子8附近区域可能是东北地区该基因缺失高发区;缺失类型与临床表型有一定的关系,当基因发生整码缺失时,临床表型为BMD,而发生移码突变时,临床表型为DMD。

Relationship of phenotype with type of deletion of dystrophin gene

OBJECTIVE: To detect the distribution characteristics of dystrophin gene deletions in the northeastern of China and the relationship of severity with type of deletion. METHODS: To screen deletion distribution of 124 DMD/BMD patients via multiplex PCR, male high-risk fetuses were detected deletion by the same method. RESULTS: The deletion frequency was 49%. Deletions located in the regions of exons 45 - 53 and exons 8 - 19 were 41 (67%) and 13 (21%) cases respectively, and in 5 (8%) cases deletions were scattered over both regions, still 2 cases (3%) were checked up deletions lying in exons 34 and 43; there were 9 cases of in-frame deletions and 49 frameshift mutations in all deletions; of 30 high-risk fetuses 10 male ones were screened deletions, who had the same deletion-segments as their probands. CONCLUSIONS: The distribution of dystrophin gene deletions in the northeastern of China cluster mainly in two hot-spots, neighboring regions of exon 8 might be a real deletion "hot spot" in this region; the phenotype is associated with the type of gene deletion, the phenotype is BMD when in-frame deletions occur; severe DMD when frameshift mutations occur. Multiplex PCR method provides the short-cuts for detecting patients and making prenatal gene diagnosis.