Uncovering novel causes and modifiers of amyotrophic lateral sclerosis by nuclear and mitochondrial genome sequencing

肌萎缩性侧索硬化症（ALS）是成人发病的运动神经元疾病中最常见的一种，其特点是进展迅速，预计患者数量增长迅速，具有遗传和临床异质性（发病年龄、发病部位、疾病侵袭性和扩散等）。尽管ALS具有较高的遗传性，但在总体患者中发现单基因病因的比例<15%，这表明仍有相当大比例的ALS疾病基因和突变有待确定。在散发的ALS患者中发现疾病遗传原因的可能性与极端表型的存在相关-例如，异常早发或非常侵袭性或轻微的疾病。最后，除了核基因组内的遗传因素外，线粒体（mt）基因组的改变（例如mtDNA突变负荷的变化）已被发现影响其他神经退行性疾病的临床表达或外显率，但从未在ALS中进行过研究。观察到的ALS表现和侵袭性的临床变异性至少可以部分地解释为众多迄今为止公认的和目前未知的遗传原因、风险因素和疾病修饰因子，每一个都代表了一种潜在的治疗途径，并影响着现在和未来的临床决策。这项提议的总体目标是通过三种互补的方法，通过核和线粒体基因组测序，在大型和临床特征良好的ALS患者队列中发现ALS的新遗传原因和修饰因子。在目标1中，我们将利用全基因组测序（WGS）方法在三个大型ALS队列中寻找（新的）ALS遗传原因，每个队列由200名患者组成；发病年龄极早，病情进展极快或极慢。在目标2中，我们将利用从目标1中具有极端临床表现的患者获得的WGS数据集，以确定影响ALS外显率和/或表型表达的遗传因素。最后，在目标3中，我们的目标是通过超深度测序筛选200名患者的mtDNA，以确定mtDNA突变负荷的变化是否影响ALS的发病年龄和进展。申请人在临床遗传学，基因组学和大规模数据分析方面具有广泛和互补的专业知识，并可访问最佳和独特的生物标本库。

Amyotrophic lateral sclerosis (ALS) is the most common type of adult-onset motor neuron disease, characterized by rapid progression, projected fast grow of the number of patients, and genetic and clinical heterogeneity (age at onset, site of onset, disease aggressiveness and spread, etc.). In spite of the high level of heritability of ALS, a monogenic etiology can be found in <15% of overall patients, indicating that a considerable proportion of ALS disease genes and mutations remain to be identified. The probability of detecting a genetic cause of disease in sporadic ALS patients correlates with the presence of extreme phenotypes – e.g., exceptionally early onset or very aggressive or mild disease. Finally, apart from genetic factors within the nuclear genome, alterations of the mitochondrial (mt) genome (e.g., changes in the mtDNA mutational load) have been found to influence clinical expression or penetrance in other neurodegenerative disorders, but have never been investigated in ALS. The observed clinical variability of ALS manifestation and aggressiveness can at least partially be explained by the multitude of hitherto recognized and currently unknown genetic causes, risk factors, and disease modifiers, each of which represents a potential therapeutic avenue and influences present and future clinical decisions. The overarching goal of this proposal is to uncover novel genetic causes and modifiers of ALS by nuclear and mitochondrial genome sequencing in large and well clinically characterized cohorts of ALS patients by three complementary approaches. In Objective 1, we will search for (novel) genetic causes of ALS by utilizing a whole-genome sequencing (WGS) approach in three large ALS cohorts, consisting of 200 patients each; with very early age at onset, extremely fast, or extremely slow disease progression, respectively. In Objective 2, we will leverage the WGS datasets obtained from patients with extreme clinical manifestations from Objective 1 in order to identify genetic factors that influence the penetrance and/or the phenotypic expression of ALS. Finally, in Objective 3, we aim to screen mtDNA from 200 patients by ultra-deep sequencing in order to determine whether changes in the mtDNA mutational load influence age at onset and progression in ALS. The applicants have extensive and complementary expertise in clinical genetics, genomics, and large-scale data analysis and access to an optimal and unique biospecimen repository.