We describe the presentation and follow-up of a three-year-old girl with nemaline myopathy due to a de-novo variant in ACTA1 (encoding skeletal alpha actin) and moderately low enzyme level of Complex I of the mitochondrial respiratory chain. She presented in the neonatal period with hypotonia, followed by weakness in the facial, bulbar, respiratory and neck flexors muscles. A biopsy of her quadriceps muscle at the age of one year showed nemaline rods. Based on her clinical presentation of a congenital myopathy and histopathological features on a muscle biopsy, ACTA1 was sequenced, and this revealed a novel sequence variant, c.760 A>C p. (Asn254His). In addition, mitochondrial respiratory chain enzymatic activity of skeletal muscle biopsy showed a moderately low activity of complex I (nicotinamide adenine dinucleotide (NADH): ubiquinone oxidoreductase). Disturbances of Complex I of the respiratory chain have been reported in patients with nemaline myopathy, although the mechanism remains unclear.

中文翻译：

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线状肌病和线粒体复合物 I 缺乏症患者中的新型 ACTA1 变异


我们描述了一名三岁女孩因 ACTA1（编码骨骼 α 肌动蛋白）的新生变异和线粒体呼吸链复合物 I 酶水平中度较低而患有线状肌病的表现和随访。她在新生儿期出现肌张力低下，随后出现面部、延髓、呼吸和颈屈肌无力。一岁时，她的股四头肌活检显示了线状杆状细胞。根据她先天性肌病的临床表现和肌肉活检的组织病理学特征，对 ACTA1 进行了测序，这揭示了一个新的序列变异，c.760 A>C p。 （Asn254His）。此外，骨骼肌活检的线粒体呼吸链酶活性显示复合物I（烟酰胺腺嘌呤二核苷酸（NADH）：泛醌氧化还原酶）的活性中等偏低。据报道，线状肌病患者的呼吸链复合物 I 受到干扰，但其机制仍不清楚。