1例误诊为强直性肌营养不良的脊髓小脑共济失调3型患者的基因诊断

Gene diagnosis of one case with spinocerebellar ataxia type 3 misdiagnosed as myotonic dystrophy

目的探讨基因诊断在临床误诊为强直性肌营养不良的3型遗传性脊髓小脑共济失调家系中的价值。方法收集家系成员外周血,提取基因组DNA,全基因组外显子测序筛查致病基因。PCR扩增患者遗传性脊髓小脑共济失调3型致病基因片段,电泳和测序鉴定异常电泳条带。结果基因诊断确诊该患者为遗传性脊髓小脑共济失调3型,并非强直性肌营养不良。该患者致病基因为杂合子,CAG重复次数分别为21次和71次。结论外显子组测序技术在孟德尔遗传病中寻找致病基因发挥了重要作用以及基因诊断对不典型脊髓小脑共济失调有很好的确诊价值,对于临床出现相类似的症状的患者或与其他疾病症状相叠加的脊髓小脑共济失调的患者,均应进行基因诊断,以免出现漏诊和误诊。

Objective To investigate the gene diagnostic value of one ease with spinocerebellar ataxia type 3 misdiagnosed as myotonie dystrophy. Methods Genomic DNA was extracted from family and exome sequencing was performed to screen pathogenic gene,whieh was amplified by PCR technique. Then abnormal electrophoretic band was identified by electrophoresis and sequence. Results The patient was definitely diagnosed as spinocerebellar ataxia type 3 rather than myotonic dystrophy. Pathogenic gene was heterozygous,which showed 71 and 21 times of CAG repeats. Conclusion The whole exome sequencing plays an improtant role in discovering disease-causing mutations coincident to Mendelian inheritance and the gene di agnosis has a good clinical diagnostic value in atypical spinoeerebellar ataxia. The patients with similar clinical symptoms or spi- nocerebellar ataxia should received gene exanimation in order to avoid the misdiagnosis and missed diagnosis.