Deficiency of the proteins involved in oxidative phosphorylation (OXPHOS) can lead to mitochondrial dysfunction. Polyribonucleotide nucleotidyltransferase 1 (PNPT1) is one of the genes involved in the OXPHOS and encodes the mitochondrial polynucleotide phosphorylase (PNPase) which is implicated in RNA-processing exoribonuclease activity. Herein, we report a 34-month-old boy who presented with global developmental delay, muscular hypotonia, hearing impairment, and movement disorders including chorea and dystonia. Mitochondrial genome sequencing and whole-exome sequencing (WES) were performed and a variant in PNPT1:c.1453A>G; p. (Met485Val) was identified. A number of patient’s neurologic problems had been already reported in previous studies, however, lower limbs spasticity and bulbar dysfunction were novel phenotypic findings. In addition, delayed myelination during infancy, progressive basal ganglia atrophy, and brain stem abnormal signals including transverse pontine fibers and superior colliculus involvement were also novel neuroimaging findings in this case. Different crystallographic modeling and stereochemical analysis of the c.1453A>G; p. (Met485Val) variant showed this variant affects the active site of the protein and disrupts the normal protein function.

参与氧化磷酸化 (OXPHOS) 的蛋白质缺乏会导致线粒体功能障碍。多核糖核苷酸核苷酸转移酶 1 (PNPT1) 是参与 OXPHOS 的基因之一，它编码与 RNA 加工外核糖核酸酶活性有关的线粒体多核苷酸磷酸化酶 (PNPase)。在此，我们报告了一名 34 个月大的男孩，他出现整体发育迟缓、肌张力减退、听力障碍和包括舞蹈症和肌张力障碍在内的运动障碍。进行了线粒体基因组测序和全外显子组测序（WES），并且在 PNPT1:c.1453A>G 中有一个变体；页。(Met485Val) 被鉴定。先前的研究已经报道了许多患者的神经系统问题，然而，下肢痉挛和延髓功能障碍是新的表型发现。此外，婴儿期髓鞘形成延迟、进行性基底节萎缩和脑干异常信号（包括横向桥脑纤维和上丘受累）也是该病例的新神经影像学发现。c.1453A>G的不同晶体学建模和立体化学分析；页。(Met485Val) 变体显示该变体影响蛋白质的活性位点并破坏正常的蛋白质功能。