Bech-Hansen, N. TorbenBarclay, Sarah2017-12-152017-12-1520172017http://hdl.handle.net/11023/4273Next-generation sequencing – and, in particular, exome sequencing, the targeted application of next-generation sequencing to the coding portion of the genome – appeared on the scene, in the last decade, as a promising new way of efficiently searching for and successfully identifying causative mutations in human disease. I have applied exome sequencing to the study of two human traits. The first is ROHHAD (Rapid-Onset Obesity with Hypoventilation, Hypothalamic Dysfunction and Autonomic Dysregulation), a rare, complex, and potentially fatal pediatric syndrome. The second is DTD (Developmental Topographical Disorientation), a novel behavioural phenotype in which individuals are unable to effectively navigate their surroundings. Though the two phenotypes themselves have little in common, they are united in the fact that both are believed to have a genetic basis, and are therefore candidates for the application of exome sequencing to search for causative mutations. The research described in this thesis has applied exome sequencing to both ROHHAD and DTD to search for causative mutations. In neither case were we able to identify causative genes, but in both cases we were able to rule out several genetic hypotheses (rare coding mutations across most of the genome), and, perhaps most importantly, we were able to rule out exome sequencing as a means of identifying disease-causing mutations for these traits. In addition to ruling out major hypotheses as to the underlying bases of these two traits, thus clearing the way for the exploration of additional hypotheses, the ROHHAD and DTD studies also provided informative illustrations of next-generation sequencing studies that do not identify causative genes. Together, they provided a framework for reporting negative results from next-generation sequencing studies, highlighting the importance of clearly reporting the data-quality, as well as ways to limit the number of false positive variant calls and considerations for the effective filtering of DNA sequence variants to ensure that the search for disease-causing candidates has been as thorough as possible.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.BioinformaticsGeneticsMedicine and SurgeryRapid-Onset ObesityHypoventilationHypothalamic DysfunctionAutonomic DysregulationDevelopmental Topographical DisorientationExome SequencingNegative ResultsNext-Generation Sequencingdoctoral thesis10.11575/PRISM/28740