Critical evaluation of the Illumina MethylationEPIC BeadChip microarray for whole-genome DNA methylation profiling

Published online: 7 October 2016Background: In recent years the Illumina HumanMethylation450 (HM450) BeadChip has provided a user-friendly platform to profile DNA methylation in human samples. However, HM450 lacked coverage of distal regulatory elements. Illumina have now released the MethylationEPIC (EPIC) BeadChip, with new content specifically designed to target these regions. We have used HM450 and whole-genome bisulphite sequencing (WGBS) to perform a critical evaluation of the new EPIC array platform. Results: EPIC covers over 850,000 CpG sites, including >90 % of the CpGs from the HM450 and an additional 413,743 CpGs. Even though the additional probes improve the coverage of regulatory elements, including 58 % of FANTOM5 enhancers, only 7 % distal and 27 % proximal ENCODE regulatory elements are represented. Detailed comparisons of regulatory elements from EPIC and WGBS show that a single EPIC probe is not always informative for those distal regulatory elements showing variable methylation across the region. However, overall data from the EPIC array at single loci are highly reproducible across technical and biological replicates and demonstrate high correlation with HM450 and WGBS data. We show that the HM450 and EPIC arrays distinguish differentially methylated probes, but the absolute agreement depends on the threshold set for each platform. Finally, we provide an annotated list of probes whose signal could be affected by cross-hybridisation or underlying genetic variation. Conclusion: The EPIC array is a significant improvement over the HM450 array, with increased genome coverage of regulatory regions and high reproducibility and reliability, providing a valuable tool for high-throughput human methylome analyses from diverse clinical samples.Ruth Pidsley, Elena Zotenko, Timothy J. Peters, Mitchell G. Lawrence, Gail P. Risbridger, Peter Molloy, Susan Van Djik, Beverly Muhlhausler, Clare Stirzaker and Susan J. Clar

Extraordinary acts and ordinary pleasures: Rhetorics of inequality in young people’s talk about celebrity

In this article, we start from the problem of inequality raised by the existence of a class of celebrities with high levels of wealth and status. We analyse how young people make sense of these inequalities in their talk about celebrity. Specifically, we revisit Michael Billig’s Talking of the Royal Family, and his focus on rhetorical strategies that legitimate inequalities of money and power. As he argued, in comparing their lives with those of the rich and famous, young people are making sense of the massive disparity between the two, often replacing envy or anger with pleasure in being ‘ordinary’. We extend Billig’s work by looking at a larger class of public figures than royalty, including those with a more permeable border between ‘them’ and ‘us’. In so doing, we expand his categories and attend to the relationship between the gender of celebrities and contemporary rhetorics of inequality.This work was supported by the Economic and Social Research Council (grant number ES/J022942/1)