晚发性线粒体疾病在诊断上具有挑战性，其疾病表现具有显着的异质性。据报告，一名 67 岁的绅士有 3 个月的癫痫病史、复发性脑病、共济失调和体重减轻，最近因终末期慢性肾病开始血液透析。广泛的检查包括进行了血清学、脑脊液、磁共振成像和脑电图检查。全外显子组测序和肌肉活检证实了诊断。大脑磁共振成像显示右颞叶有单一非增强 T2 液减弱反转恢复高信号皮质/皮质下信号变化和小脑萎缩。鉴于病因不明的亚急性表现，他接受了自身免疫性/副肿瘤性脑炎的经验治疗。尽管两周后皮质异常的放射学解决了，但临床上没有改善。进一步的附带病史揭示了轻度共济失调步态和长期听力损失，提示遗传原因。全外显子组测序揭示了 MT-TV 基因中可能存在致病性异质性线粒体 DNA 变异 m.1659T>C，与其他有丝分裂组织相比，肌肉中存在更高水平的异质性 (91%)。开始高脂肪/蛋白质饮食和包括辅酶 Q10 在内的多种维生素。治疗营养缺乏症并避免因脑病继发的不可靠口服摄入而导致的间歇性禁食可能有助于在接下来的几个月内看到临床改善，脑病得到缓解并恢复到基线步态和体重。报告了一个成人病例具有类似脑炎的急性神经症状，由异质性 m.1659T>C MT-TV 变体引起，之前曾报道过在表现出不同临床表型的儿童中出现过一次。© 2024 作者。约翰·威利出版的《欧洲神经病学杂志》

Late-onset mitochondrial disorders are diagnostically challenging with significant heterogeneity in disease presentation. A case is reported of a 67-year-old gentleman who presented with a 3-month history of seizures, recurrent encephalopathy, ataxia and weight loss, preceded by recent initiation of haemodialysis for end-stage chronic kidney disease.Extensive work-up including serological, cerebrospinal fluid, magnetic resonance imaging and electroencephalography was performed. Whole exome sequencing and muscle biopsy confirmed the diagnosis.Magnetic resonance imaging brain demonstrated a single non-enhancing T2 fluid attenuated inversion recovery hyperintense cortical/subcortical signal change in the right temporal lobe and cerebellar atrophy. Given the subacute presentation of uncertain aetiology, he was empirically treated for autoimmune/paraneoplastic encephalitis. Despite radiological resolution of the cortical abnormality 2 weeks later, there was no clinical improvement. Further collateral history unveiled a mildly ataxic gait and longstanding hearing loss suggestive of a genetic cause. Whole exome sequencing revealed a likely pathogenic, heteroplasmic mitochondrial DNA variant in the MT-TV gene, m.1659T>C, present at higher levels of heteroplasmy in muscle (91%) compared to other mitotic tissues. A high fat/protein diet and multivitamins including co-enzyme Q10 were commenced. Treatment of the nutritional deficiency and avoidance of intermittent fasting due to unreliable oral intake secondary to encephalopathy probably contributed to the clinical improvement seen over the ensuing few months, with resolution of his encephalopathy and return to his baseline gait and weight.An adult case is reported with an acute neurological presentation mimicking encephalitis, caused by a heteroplasmic m.1659T>C MT-TV variant, previously reported once in a child who displayed a different clinical phenotype.© 2024 The Author(s). European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.