We describe a novel mitochondrial variant (m.5865T>C) in a patient with decreased exercise endurance and juvenile onset slowly progressive bilateral ptosis without opthamloparesis. The m.5865T>C variant was seen in 82.9% of mtDNA molecules in skeletal muscle tissue and ∼8% of mtDNA molecules in urine epithelium, but was not detected in blood leukocytes. The proband does not demonstrate any additional features often seen in individuals with a mitochondrial disorder (i.e., sensorineural hearing loss, type 2 diabetes, stroke-like episodes, muscle weakness, ophthalmoparesis, cardiomyopathy or cardiac arrhythmias). This case suggests that ptosis and exercise intolerance, without ophthalmoparesis, are the primary clinical features of the m.5865T>C mtDNA variant.

中文翻译：

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线粒体疾病伴有上睑下垂和运动不耐受，无继发于 m.5865T>C 变异的眼肌麻痹

我们描述了一种新的线粒体变异（m.5865T>C），患者的运动耐力下降，青少年发病缓慢，双侧上睑下垂，无视眼轻瘫。m.5865T>C 变异见于骨骼肌组织中 82.9% 的 mtDNA 分子和尿液上皮中约 8% 的 mtDNA 分子，但在血液白细胞中未检测到。先证者没有表现出在患有线粒体疾病的个体中常见的任何其他特征（即，感音神经性听力损失、2 型糖尿病、中风样发作、肌肉无力、眼肌麻痹、心肌病或心律失常）。该病例表明，没有眼肌麻痹的上睑下垂和运动不耐受是 m.5865T>C mtDNA 变异的主要临床特征。