Pathogenic Bi-allelic Mutations in NDUFAF8 Cause Leigh Syndrome with an Isolated Complex I Deficiency
Pathogenic Bi-allelic Mutations in NDUFAF8 Cause Leigh Syndrome with an Isolated Complex I Deficiency
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DOI：
10.1016/j.ajhg.2019.12.001
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发表时间：
2020-01-02
影响因子：
9.8
通讯作者：
Taylor, Robert W.
中科院分区：
文献类型：
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作者：
Alston, Charlotte L.;Veling, Mike T.;Taylor, Robert W.
Leigh 综合征是儿科线粒体疾病表现中最常见的神经表型之一。其特征是神经影像学发现基底节、丘脑和脑干对称性病变，以及运动技能丧失和发育里程碑延迟。 Leigh 综合征的基因诊断非常复杂，因为迄今为止已报道了超过 75 个候选疾病相关基因，存在巨大的遗传异质性。候选基因仍在不断涌现，当“组学”工具（基因组学、蛋白质组学和转录组学）应用于操纵细胞系和缺乏基因诊断的临床特征个体群体时，候选基因就会被识别出来。 NDUFAF8 就是这样一种蛋白质；在大规模蛋白质-蛋白质相互作用筛选中，发现它与已充分表征的复合物 I (CI) 组装因子 NDUFAF5 相互作用。诊断性下一代测序已识别出三名不相关的儿科受试者，每名受试者均临床诊断为 Leigh 综合征，他们在 NDUFAF8 中携带双等位基因致病变异。这些变体包括循环剪接变体，该变体最初由于其深内含子位置而被忽视。发现受试者成纤维细胞表达复合物 I 缺陷，用野生型 NDUFAF8-cDNA 进行慢病毒转导可改善组装缺陷和生化缺陷。受试成纤维细胞的复合体分析表明存在复合物 I 组装缺陷，而停滞的组装中间体证实了 NDUFAF8 在早期复合物 I 组装中的作用。该报告旨在扩大与 Leigh 综合征相关的遗传异质性，并验证孤儿蛋白表征的临床实用性。我们还强调了在诊断测试期间鉴定出单个明确致病性变异时评估内含子序列的重要性。
Leigh syndrome is one of the most common neurological phenotypes observed in pediatric mitochondrial disease presentations. It is characterized by symmetrical lesions found on neuroimaging in the basal ganglia, thalamus, and brainstem and by a loss of motor skills and delayed developmental milestones. Genetic diagnosis of Leigh syndrome is complicated on account of the vast genetic heterogeneity with >75 candidate disease-associated genes having been reported to date. Candidate genes are still emerging, being identified when "omics" tools (genomics, proteomics, and transcriptomics) are applied to manipulated cell lines and cohorts of clinically characterized individuals who lack a genetic diagnosis. NDUFAF8 is one such protein; it has been found to interact with the well-characterized complex I (CI) assembly factor NDUFAF5 in a large-scale protein-protein interaction screen. Diagnostic next-generation sequencing has identified three unrelated pediatric subjects, each with a clinical diagnosis of Leigh syndrome, who harbor bi-allelic pathogenic variants in NDUFAF8. These variants include a recurrent splicing variant that was initially overlooked due to its deep-intronic location. Subject fibroblasts were found to express a complex I deficiency, and lentiviral transduction with wild-type NDUFAF8-cDNA ameliorated both the assembly defect and the biochemical deficiency. Complexome profiling of subject fibroblasts demonstrated a complex I assembly defect, and the stalled assembly intermediates corroborate the role of NDUFAF8 in early complex I assembly. This report serves to expand the genetic heterogeneity associated with Leigh syndrome and to validate the clinical utility of orphan protein characterization. We also highlight the importance of evaluating intronic sequence when a single, definitively pathogenic variant is identified during diagnostic testing.