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Genetic and genomic investigations of Amyotrophic lateral sclerosis

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thesis
posted on 28.03.2022, 17:00 by Emily Pamela McCann
Amyotrophic lateral sclerosis (ALS) is a fatal, genetically heterogeneous neurodegenerative disease characterised by the loss of upper and lower motor neurons. Gene mutations remain the only proven cause of ALS. While 10% of patients have a family history (familial ALS; FALS), one third of these patients carry an unidentified causal mutation. Among the remaining 90% of apparently sporadic patients (sporadic ALS; SALS), less than 10% carry a known causal mutation. As such, a significant amount of genetic variation underlying ALS remains to be discovered. This thesis presents innovative approaches to identify novel genetic causes of ALS using next-generation sequencing (NGS). This involved the development and application of various bioinformatics strategies to whole-exome (WES) and whole-genome (WGS) sequencing datasets for various patient cohorts including FALS patients, families and ALS-discordant monozygotic twins. Assessment of the prevalence of known and candidate ALS genes among Australian patients revealed that 39.2% of FALS had an unidentified causal gene mutation, and identified eight candidate ALS mutations. Novel ALS gene discovery in four small families identified 19, 11, 16 and 64 candidate causal mutations in each. Having exhausted the genetic power of these families, an in silico pipeline was developed to assess the potential pathogenicity of each candidate mutation. This showed that five, six, one and 11 candidate mutations had a high potential to cause ALS. Gene discovery efforts in a fifth family using WES, WGS and genetic linkage data failed to identify any candidate mutations, however narrowed the search to just 14% of the genome. WGS of four ALS-discordant monozygotic twinsets also failed to identify any de novo mutations underlying disease discordance. This work expands our understanding of the genetic causes of ALS, and in turn provides much needed insight for the development of diagnostic and carrier-screening regimes, as well as relevant models of disease.

History

Table of Contents

1. Introduction -- 2. General subjects and methods -- 3. Development of strategies and pipelines for analysing NGS data -- 4. Analysis of known ALS genes -- 5. Investigation of candidate ALS genes -- 6. Novel disease gene discovery in ALS families -- 7. Searching for genetic differences between ALS-discordant monozygotic twins -- 8. Discussion -- Appendices -- References.

Notes

Bibliography: pages 513-594 Thesis by publication.

Awarding Institution

Macquarie University

Degree Type

Thesis PhD

Degree

PhD, Macquarie University, Faculty of Medicine and Health Sciences, Department of Biomedical Sciences

Department, Centre or School

Department of Biomedical Sciences

Year of Award

2019

Principal Supervisor

Ian Blair

Rights

Copyright Emily Pamela McCann 2019. Copyright disclaimer: http://mq.edu.au/library/copyright

Language

English

Extent

1 online resource (xxviii, 594 pages) diagrams, graphs, tables

Former Identifiers

mq:72152 http://hdl.handle.net/1959.14/1281913