title: Twin methodology in epigenetic studies.
abstract: Since the final decades of the last century, twin studies have made a remarkable contribution to the genetics of human complex traits and diseases. With the recent rapid development in modern biotechnology of high-throughput genetic and genomic analyses, twin modelling is expanding from analysis of diseases to molecular phenotypes in functional genomics especially in epigenetics, a thriving field of research that concerns the environmental regulation of gene expression through DNA methylation, histone modification, microRNA and long non-coding RNA expression, etc. The application of the twin method to molecular phenotypes offers new opportunities to study the genetic (nature) and environmental (nurture) contributions to epigenetic regulation of gene activity during developmental, ageing and disease processes. Besides the classical twin model, the case co-twin design using identical twins discordant for a trait or disease is becoming a popular and powerful design for epigenome-wide association study in linking environmental exposure to differential epigenetic regulation and to disease status while controlling for individual genetic make-up. It can be expected that novel uses of twin methods in epigenetic studies are going to help with efficiently unravelling the genetic and environmental basis of epigenomics in human complex diseases.
authors.affiliation: Epidemiology, Biostatistics and Bio-demography, Institute of Public Health, University of Southern Denmark, DK-5000, Odense C, Denmark Human Genetics, Institute of Clinical Research, University of Southern Denmark, DK-5000, Odense C, Denmark qtan@health.sdu.dk.
authors.forename: Qihua
authors.initials: Q
authors.lastname: Tan
authors.affiliation: Epidemiology, Biostatistics and Bio-demography, Institute of Public Health, University of Southern Denmark, DK-5000, Odense C, Denmark Human Genetics, Institute of Clinical Research, University of Southern Denmark, DK-5000, Odense C, Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Christiansen
authors.affiliation: Epidemiology, Biostatistics and Bio-demography, Institute of Public Health, University of Southern Denmark, DK-5000, Odense C, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: von Bornemann Hjelmborg
authors.affiliation: Epidemiology, Biostatistics and Bio-demography, Institute of Public Health, University of Southern Denmark, DK-5000, Odense C, Denmark Human Genetics, Institute of Clinical Research, University of Southern Denmark, DK-5000, Odense C, Denmark.
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
mesh_terms: D000375:Aging / Q000235:genetics; D004194:Disease / Q000235:genetics; D044127:Epigenesis, Genetic; D048788:Growth and Development / Q000235:genetics; D006801:Humans; D018433:Twin Studies as Topic; D014427:Twins / Q000235:genetics*
keywords: Complex phenotypes; Epigenomics; Twins