Genome-wide
association studies (GWAS) have rapidly spread across the globe over the last
few years becoming the de facto approach to identify candidate regions
associated with complex diseases in human medicine. GWAS and genome analysis
are also powerful tools to provide a handle on genetic variation in a wide
range of traits important for human health, agriculture, conservation, and the
evolutionary history of life. As the technology matured and results from the
various studies came to light, a clear picture emerged that, as often seems to
be the case, biological processes prove to be much more complex than we would
want them to be. While many new insights were and are being attained, maybe
just as many new questions emerged. In many cases, GWAS successfully identified
variants that were unquestionably associated with variation in traits and, in
some cases, culminated in the discovery of the causal variant(s) and its
mechanism of action. In other cases, these studies evidenced that a large
number of traits are highly polygenic, and, instead of identifying a few
genomic region culprits, we saw a scattering of effects across the whole
genome. While in these latter cases the underlying biology largely remains
elusive, it still allows making predictions of phenotypes based on the genomic
information of an individual. And this in the short term might be even more
important for translational outcomes. This brings us to the focus of this
volume in the series Methods in Molecular Biology: Genome-Wide Association
Studies and Genomic Prediction.
This volume in
the series covers from the preliminary stages of understanding the phenotypes
of interest and design issues for GWAS, passing through efficient computational
methods to store and handle large datasets, quality control measures, phasing, haplotype
inference and imputation, and moving on to then discuss the various statistical
approaches to data analysis where the experimental objective is either to nail
down the biology by identifying genomic regions associated to a trait or to use
the data to make genomic predictions about a future phenotypic outcome (e.g.
predict onset of disease). One of the chapters even merges the two approaches
into a unified framework.
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