Identification and Selection of CpG sites Sample Clauses

Identification and Selection of CpG sites. The number of CpG sites required for epigenetic-clock development depend on many factors such as tissue type, assay design, biological and technical variability. Ideally, a reduced set of age-informative CpGs should be identified for each species/group of species if universal epigenetic-clocks are envisaged. Once these sites identified, specific assays to type them which could be quite cost- effective (5-10€) can be developed. But first, the sites need to be selected, which requires some initial investment. Although the final set of age-diagnostic CpGs could be of tens or hundreds, the largest the number of CpGs analyzed to select the final set, the more precision the clock will have. For example, studies in mouse started from about 1 million CpG sites to select a final set of 329 (Xxxxxx et al. 2017), studies in wolves and dogs started from about 200K CpGs to select a final set of 115 (Xxxxxxxx et al. 2017). Several alternatives for discovering age-informative CpG sites are possible, going from candidate gene selection, transfer of previously identified CpGs from other species or identifying new CpGs based on a reduced fraction or on the whole genome. The epigenetic-clock studies on fish performed to date have used different approaches for selecting age-informative CpG sites.