The identification of the m.4412G > A MT-TM (mt-tRNA^Met) mutation was first reported in 2019. The affected individual presented with childhood-onset seizures and myopathy and bilateral basal ganglia changes, with heteroplasmy levels in muscle as high as 90%. Here, we describe another adult-onset patient with the same mutation and additional phenotypes, including hearing impairment, cerebellar ataxia, progressive dementia, and myopathy. The 10% heteroplasmy level observed in skin fibroblasts from this patient are lower than those in the previously reported patient. Our report suggests possible clinical heterogeneity in patients with mitochondrial tRNA mutations based on heteroplasmy levels.

2019 年首次报道了 m.4412G > A MT-TM (mt-tRNA ^Met ) 突变的鉴定。受影响的个体出现儿童期癫痫发作和肌病以及双侧基底神经节变化，肌肉中的异质性水平高达90%。在这里，我们描述了另一名具有相同突变和其他表型的成年发病患者，包括听力障碍、小脑共济失调、进行性痴呆和肌病。在该患者的皮肤成纤维细胞中观察到的 10% 异质性水平低于先前报道的患者。我们的报告表明，基于异质性水平的线粒体 tRNA 突变患者可能存在临床异质性。