@ARTICLE{10.3389/fimmu.2014.00128, AUTHOR={Selmi, Carlo and Cavaciocchi, Francesca and Lleo, Ana and Cheroni, Cristina and De Francesco, Raffaele and Lombardi, Simone A. and De Santis, Maria and Meda, Francesca and Raimondo, Maria Gabriella and Crotti, Chiara and Folci, Marco and Zammataro, Luca and Mayo, Marlyn J. and Bach, Nancy and Shimoda, Shinji and Gordon, Stuart C. and Miozzo, Monica and Invernizzi, Pietro and Podda, Mauro and Scavelli, Rossana and Martin, Michelle R. and Seldin, Michael F. and LaSalle, Janine M. and Gershwin, M. Eric}, TITLE={Genome-Wide Analysis of DNA Methylation, Copy Number Variation, and Gene Expression in Monozygotic Twins Discordant for Primary Biliary Cirrhosis}, JOURNAL={Frontiers in Immunology}, VOLUME={5}, YEAR={2014}, URL={https://www.frontiersin.org/articles/10.3389/fimmu.2014.00128}, DOI={10.3389/fimmu.2014.00128}, ISSN={1664-3224}, ABSTRACT={Primary biliary cirrhosis (PBC) is an uncommon autoimmune disease with a homogeneous clinical phenotype that reflects incomplete disease concordance in monozygotic (MZ) twins. We have taken advantage of a unique collection consisting of genomic DNA and mRNA from peripheral blood cells of female MZ twins (nā€‰=ā€‰3 sets) and sisters of similar age (nā€‰=ā€‰8 pairs) discordant for disease. We performed a genome-wide study to investigate differences in (i) DNA methylation (using a custom tiled four-plex array containing tiled 50-mers 19,084 randomly chosen methylation sites), (ii) copy number variation (CNV) (with a chip including markers derived from the 1000 Genomes Project, all three HapMap phases, and recently published studies), and/or (iii) gene expression (by whole-genome expression arrays). Based on the results obtained from these three approaches we utilized quantitative PCR to compare the expression of candidate genes. Importantly, our data support consistent differences in discordant twins and siblings for the (i) methylation profiles of 60 gene regions, (ii) CNV of 10 genes, and (iii) the expression of 2 interferon-dependent genes. Quantitative PCR analysis showed that 17 of these genes are differentially expressed in discordant sibling pairs. In conclusion, we report that MZ twins and sisters discordant for PBC manifest particular epigenetic differences and highlight the value of the epigenetic study of twins.} }