Somatic Mutations in Single Human Neurons from Patients with Congenital Neurodegenerative Diseases

It has been hypothesized that accumulating DNA lesions in neurons contribute to aging and neurodegeneration. Despite their pathophysiological importance, the DNA lesions have not been systematically examined with effective methods. In this study, we developed a computational method for detecting genomic deletions in single-cell whole-genome sequencing (scWGS) data, and analyzed the whole genome of human single neurons. Single neurons were obtained from neurotypical individuals of various ages and from patients with three different congenital neurodegenerative diseases: Ataxia telangiectasia (AT), Cockayne syndrome (CS), and Xeroderma pigmentosum (XP). Single-neuron WGS data of AT brains are released here, and the data of other two diseases are released in a separate dbGaP study (phs001485).To understand the molecular mechanisms underlying AT, we performed single-nucleus RNA-sequencing (snRNA-seq) of postmortem cerebellar vermis and prefrontal cortex from individuals with AT and controls. To genetically confirm the diagnosis of AT, we also performed WGS on postmortem brain tissue from each individual with AT. Induced pluripotent stem cells (iPSCs) from individuals with AT and controls were differentiated into microglia, and the transcriptomes were profiled with bulk RNA-sequencing (RNA-seq).]]>
Our current single-neuron whole-genome sequencing (WGS) protocol requires us to use frozen brains, but we were not able to produce high-quality sequencing data from neurons isolated from frozen brains. Thus, we did low-coverage sequencing of whole-genome amplified DNA first, and then selected a subset of cells that had high enough amplification quality to perform high-depth single-neuron WGS. The evenness of genome amplification was measured using the median absolute pairwise difference (MAPD) metric.]]>