Mitochondrial myopathy is a group of multi-system diseases in which mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) defects lead to structural and functional dysfunction of mitochondria. The clinical manifestations of mitochondrial myopathy are complex and varied, and the testing for mtDNA and nDNA is not widely available, so misdiagnosis or missed diagnosis is common. Chronic progressive external ophthalmoplegia (CPEO) is a common type of mitochondrial myopathy, which is characterized by blepharoptosis. Here we report a 38-year-old female with mitochondrial myopathy presented with chronic numbness and weakness of the limbs, accompanied by blepharoptosis that was recently noticed. Laboratory and head magnetic resonance imaging (MRI) examinations showed no obvious abnormalities. Muscle and nerve biopsies showed characteristic ragged red fibers (RRFs) and large aggregates of denatured mitochondria. Testing for mtDNA and nDNA showed a known mutation c.2857C>T (p.R953C) and a novel variant c.2391G>C (p.M797I) in the polymerase gamma (POLG)gene, so the patient was diagnosed as mitochondrial myopathy. Clinicians should pay more attention to long-term unexplained skeletal muscle diseases with recent onset blepharoptosis. Histopathologic examination and genetic testing are of great value in the early diagnosis and therapeutic intervention.
线粒体肌病是一组线粒体DNA(mitochondrial DNA，mtDNA)或核DNA(nuclear DNA，nDNA)缺陷导致的线粒体结构和功能障碍的多系统疾病。线粒体肌病的临床表现复杂多样，而临床并未普及mtDNA和nDNA的检测，因此误诊或漏诊的情况并不少见。慢性进行性眼外肌麻痹(chronic progressive external ophthalmoplegia，CPEO)是线粒体肌病的一种常见类型，其特征为上睑下垂。本文报告1例38岁的线粒体肌病女性患者，患者临床表现为慢性的四肢麻木和无力，并伴有新发现的上睑下垂。实验室检查及头部MRI检查均未见明显异常。肌肉和神经活检结果显示特征性破碎红色纤维(ragged red fibers，RRFs)和变性线粒体的大量聚集。MtDNA和nDNA检测证实γ-多聚酶(polymerase gamma，POLG)基因存在已知的突变c.2857C>T(p.R953C)和新的突变体c.2391G>C(p.M797I)，故诊断考虑为线粒体肌病。临床医生应该注意长期原因不明的骨骼肌疾病和近期首发出现的上睑下垂。组织病理学检查和基因检测在早期诊断和治疗干预中具有重要价值。.
线粒体肌病是一组线粒体DNA(mitochondrial DNA，mtDNA)或核DNA(nuclear DNA，nDNA)缺陷导致的线粒体结构和功能障碍的多系统疾病。线粒体肌病的临床表现复杂多样，而临床并未普及mtDNA和nDNA的检测，因此误诊或漏诊的情况并不少见。慢性进行性眼外肌麻痹(chronic progressive external ophthalmoplegia，CPEO)是线粒体肌病的一种常见类型，其特征为上睑下垂。本文报告1例38岁的线粒体肌病女性患者，患者临床表现为慢性的四肢麻木和无力，并伴有新发现的上睑下垂。实验室检查及头部MRI检查均未见明显异常。肌肉和神经活检结果显示特征性破碎红色纤维(ragged red fibers，RRFs)和变性线粒体的大量聚集。MtDNA和nDNA检测证实γ-多聚酶(polymerase gamma，POLG)基因存在已知的突变c.2857C>T(p.R953C)和新的突变体c.2391G>C(p.M797I)，故诊断考虑为线粒体肌病。临床医生应该注意长期原因不明的骨骼肌疾病和近期首发出现的上睑下垂。组织病理学检查和基因检测在早期诊断和治疗干预中具有重要价值。
Keywords: blepharoptosis; histopathologic examination; mitochondrial DNA; mitochondrial myopathy; nuclear DNA.