Whole Exome Sequencing Sample Clauses

Whole Exome Sequencing. The exome is defined as the whole coding sequence found in DNA. Whole exome sequencing (XXX) is a technique of massively parallel sequencing of all the protein coding regions of DNA (Xxxxxxxx et al. 2010). Its first application was described by Xx et al when they confirmed mutations in myosin heavy chain 3 gene (MYH3) in 12 individuals with Xxxxxxx-Xxxxxxx syndrome (OMIM#193700) by targeted capture and parallel sequencing (Xx et al. 2009). The process involves initial DNA shearing and creation of a shotgun library of DNA fragments, flanked by adaptors. The library is then enriched for the exon sequences parts with the fragments being hybridized to biotinylated DNA or RNA baits. These fragments are then recovered by biotin-streptavidin-based pull down, followed by amplification and parallel sequencing of the library, mapping and calling of the identified variants. As the data generated encompass between 20,000-24,000 variants per exome, it makes it challenging to differentiate between incidental and causal variants. The best approach in resolving this problem is firstly a meticulous filtering of the data; secondly, the stratification of the results based on the predicted effect at a protein level. Both approaches to the data can navigate successfully the search for the causal gene. The mode of inheritance and pedigree information availability can also narrow down the search for candidate genes (Bamshad et al. 2011). The use of WES for disease gene identification, however, does generate some ethical considerations if samples are not anonymised: the management of genetic results generated from each individual and the disclosure to the patients, both of which are not clearly defined yet, and the limitations in the consent obtained prior to the era of WES (Xxxxxxxxx et al. 2014). The cost and time of the WES have been dramatically reduced over recent years making it a powerful tool in the discovery of the genetic basis of Mendelian and complex trait diseases. In our project, patients were previously consented for research investigations in accordance to our local R&D guidelines and samples were anonymised.