Rusanen H, Majamaa K, Tolonen U, Remes A M, Myllylä R, Hassinen I E
Department of Neurology, University of Oulu, Finland.
Neurology. 1995 Jun;45(6):1188-92. doi: 10.1212/wnl.45.6.1188.
A novel feature of demyelinating polyneuropathy was observed in a patient with the tRNA(Leu(UUR)) mutation at base pair 3243 of the mitochondrial DNA. Based on electrodiagnostic examination, the polyneuropathy was defined as being of the demyelinating, mixed (motor more than sensory) type. In a 1-year follow-up we observed approximately 7% reduction in both the motor and sensory conduction velocities. The other clinical features of the proband included a mild to moderate cognitive impairment and a combined hearing loss with a moderate sensorineural component. The proportion of the mutant genome found in the muscle of the proband was 29%, but the mutation was not found in his blood. A wide variability of the clinical phenotype was observed in the family of the proband. Heteroplasmic mutation was detected in the blood of most family members. The proportion of abnormal mitochondrial DNA was highest in the proband's brother, who had clinically definite mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, while the mutant genome was less frequent or absent in the subjects with less severe phenotypes and in healthy individuals. The findings on this pedigree emphasize the need for studies of complete families in the search for new clinical phenotypes of mutations in mitochondrial DNA.
在线粒体DNA第3243碱基对处存在tRNA(Leu(UUR))突变的一名患者中，观察到脱髓鞘性多发性神经病的一个新特征。根据电诊断检查，该多发性神经病被定义为脱髓鞘性、混合型（运动症状多于感觉症状）。在1年的随访中，我们观察到运动和感觉传导速度均下降了约7%。先证者的其他临床特征包括轻度至中度认知障碍以及伴有中度感音神经性成分的混合性听力损失。在先证者肌肉中发现的突变基因组比例为29%，但在其血液中未发现该突变。在先证者家族中观察到临床表型的广泛变异性。在大多数家族成员的血液中检测到异质性突变。在先证者的哥哥中，异常线粒体DNA的比例最高，他患有临床确诊的线粒体肌病、脑病、乳酸酸中毒和卒中样发作（MELAS）综合征，而在表型较轻的个体和健康个体中，突变基因组的频率较低或不存在。该家系的研究结果强调，在寻找线粒体DNA突变的新临床表型时，需要对完整的家族进行研究。
