title: Intra-Monozygotic Twin Pair Discordance and Longitudinal Variation of Whole-Genome Scale DNA Methylation in Adults.
abstract: Monozygotic twins share identical genomic DNA and are indistinguishable using conventional genetic markers. Increasing evidence indicates that monozygotic twins are epigenetically distinct, suggesting that a comparison between DNA methylation patterns might be useful to approach this forensic problem. However, the extent of epigenetic discordance between healthy adult monozygotic twins and the stability of CpG loci within the same individual over a short time span at the whole-genome scale are not well understood. Here, we used Infinium HumanMethylation450 Beadchips to compare DNA methylation profiles using blood collected from 10 pairs of monozygotic twins and 8 individuals sampled at 0, 3, 6, and 9 months. Using an effective and unbiased method for calling differentially methylated (DM) CpG sites, we showed that 0.087%-1.530% of the CpG sites exhibit differential methylation in monozygotic twin pairs. We further demonstrated that, on whole-genome level, there has been no significant epigenetic drift within the same individuals for up to 9 months, including one monozygotic twin pair. However, we did identify a subset of CpG sites that vary in DNA methylation over the 9-month period. The magnitude of the intra-pair or longitudinal methylation discordance of the CpG sites inside the CpG islands is greater than those outside the CpG islands. The CpG sites located on shores appear to be more suitable for distinguishing between MZ twins.
authors.affiliation: Shanghai Key Laboratory of Forensic Medicine, Institute of Forensic Sciences, Ministry of Justice, P.R. China, Shanghai, 200063, P.R. China; State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, 200433, P.R. China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory of Forensic Medicine, Institute of Forensic Sciences, Ministry of Justice, P.R. China, Shanghai, 200063, P.R. China.
authors.forename: Shumin
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Shanghai Key Laboratory of Forensic Medicine, Institute of Forensic Sciences, Ministry of Justice, P.R. China, Shanghai, 200063, P.R. China; State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, 200433, P.R. China.
authors.forename: Su-Hua
authors.initials: SH
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, 200433, P.R. China.
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, 200433, P.R. China.
authors.forename: Daru
authors.initials: D
authors.lastname: Lu
authors.affiliation: Shanghai Key Laboratory of Forensic Medicine, Institute of Forensic Sciences, Ministry of Justice, P.R. China, Shanghai, 200063, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Shen
authors.affiliation: Shanghai Key Laboratory of Forensic Medicine, Institute of Forensic Sciences, Ministry of Justice, P.R. China, Shanghai, 200063, P.R. China.
authors.forename: Chengtao
authors.initials: C
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D018899:CpG Islands; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D053803:Forensic Genetics; D005819:Genetic Markers; D015894:Genome, Human; D006801:Humans; D008297:Male; D008875:Middle Aged; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D015203:Reproducibility of Results; D014430:Twins, Monozygotic / Q000235:genetics*
chemical_list: D005819:Genetic Markers