Born Alfred Peter, Duno Morten, Rafiq Jabin, Risom Lotte, Wibrand Flemming, Østergaard Elsebet, Vissing John
Paediatric Clinic, University of Copenhagen, Rigshospitalet, Denmark.
Department of Clinical Genetics, University of Copenhagen, Rigshospitalet, Denmark.
Eur J Paediatr Neurol. 2015 Jan;19(1):69-71. doi: 10.1016/j.ejpn.2014.10.006. Epub 2014 Nov 1.
A 10-year-old girl presented with exercise intolerance, learning difficulty, and muscle weakness in a limb girdle distribution. She had delayed achievement of motor milestones and difficulties with social interaction at pre-school age. Muscle biopsy showed no myopathic or dystrophic features, but 90% COX negative fibres and ragged blue fibres. Respiratory chain enzyme analysis in muscle showed a combined deficiency and mitochondrial DNA sequencing revealed the presence of an m.4450G>A mutation in the MT-TM gene encoding the tRNA for methionine. The mutation was only detected in mtDNA extracted from muscle and skin fibroblast, and could not be found in other tissues or in the mother. This is the second patient reported in the literature with a mitochondrial myopathy due to a mt-tRNA(Met) mutation. The first patient, a 30-year-old woman, presented with exercise intolerance, limb girdle muscle weakness, lactic acidosis, learning difficulty, and growth retardation in early childhood. Thus, the two patients exhibit strikingly overlapping phenotypes.
一名10岁女孩出现运动不耐受、学习困难以及肢体带型分布的肌肉无力症状。她运动发育里程碑延迟，在学龄前存在社交互动困难。肌肉活检未显示肌病或营养不良特征，但有90%的细胞色素氧化酶（COX）阴性纤维和破碎红纤维。肌肉呼吸链酶分析显示存在联合缺陷，线粒体DNA测序揭示在编码甲硫氨酸tRNA的MT - TM基因中存在m.4450G>A突变。该突变仅在从肌肉和皮肤成纤维细胞提取的线粒体DNA中检测到，在其他组织或母亲中未发现。这是文献报道的第二例因线粒体tRNA（Met）突变导致线粒体肌病的患者。首例患者是一名30岁女性，表现为运动不耐受、肢体带型肌肉无力、乳酸性酸中毒、学习困难以及幼儿期生长发育迟缓。因此，这两名患者表现出明显重叠的表型。
