Epigenome-wide association study (EWAS): Methods and applications

Since their inception less than a decade ago, epigenome-wide association studies (EWAS) have become widely adopted to help decipher disease etiology and to identify disease-specific biomarkers. In this chapter we will address the concept of EWAS by providing a background on genetic epidemiology studies to set a historical context for the initiation of genome-wide association studies (GWAS) that paved the way for widespread adoption of EWAS. We will introduce the field of epigenetics focusing on DNA methylation and address specific considerations for EWAS study design, sample selection, sample heterogeneity and confounding. Lastly, will review past, present and emerging technologies for genome-wide DNA methylation detection that can be used to perform EWAS studies, to showcase their advantages and shortcomings.