肌阵挛癫痫合并破碎红纤维综合征的线粒体DNA突变特点

目的　探讨肌阵挛癫痫伴破碎红纤维综合征 ( MERRF)的分子遗传学特点。方法　用聚合酶链反应-限制片段长度多态性 ( PCR- RFL P)方法检测 6例 MERRF患者及其部分母系亲属的肌肉和 (或 )外周血细胞的mt DNA的 A8344 G点突变 ,并进行突变型 mt DNA的定量分析。结果　在 2例患者的肌肉和外周血细胞中检测到A8344 G点突变。但其母亲的外周血细胞中未能检测到此突变。这 2例 A8344 G阳性标本中 ,肌肉组织的突变型mt DNA的比例分别为 79.0 %和 86 .8%,而在外周血细胞中分别为 5 9.7%和 72 .9%,突变型 m t DNA的比例在肌肉组织中高于外周血细胞中。结论　在 MERRF患者不同组织中检测到 mt DNA A8344 G点突变 ,与国外报道一致。但国外报道 MERRF多为母系遗传 ,而我们的病例未能有此发现 ,须扩大样本量进一步分析。

Analysis of mitochondrial DNA A8344G point mutation in 6 cases with myoclonic epilepsy and ragged-red fiber disease

Objective To study the characteristics of molecular genetics concerning Chinese myoclonic epilepsy and ragged-red fiber disease (MERRF).Methods A8344G point mutation in the mitochondrial DNA (mtDNA) of muscle and (or) blood cells were investigated in 6 patients with MERRF and some of their relatives from 6 families by PCR-RFLP. Mutation mtDNA in the sample harboring mutation was quantitatively analyzed. Results The mtDNA A8344G point mutation was identified in muscle and blood of 2 cases, but not in blood of their relatives. The proportion of mtDNA A8344G was 79.0% and 86.8% in muscle as well as 59.7% and 72.9 in blood. Conclusion MtDNA A8344G mutation exists in the patients with MERRF in our study and can be detected in various tissues, which is consistent with reports abroad. However, the 2 cases are sporadic rather than maternal inherited. Whether the mutation is due to ethnic difference or sporadic event needs to be investigated further.