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Mol Biol Rep (2013) 40:52755280 DOI 10.1007/s11033-013-2627-y
Differences of DNA methylation proles between monozygotic twins blood samples
Chengtao Li Shumin Zhao Na Zhang
Suhua Zhang Yiping Hou
Received: 17 July 2012 / Accepted: 30 April 2013 / Published online: 7 May 2013 Springer Science+Business Media Dordrecht 2013
Abstract Monozygotic twins (MZs) share an identical genomic sequence, which makes it impossible to discriminate one another with conventional genetic markers like STRs. On the other hand, phenotypic discordance between MZs implies the existence of different epigenetic characteristics. DNA methylation, an essential epigenetic modication, however, might be a potential biomarker to solve the forensic puzzle. In this study, we examined 22 pairs of MZs with a methylation BeadChip including 27,578 CpG sites. The results suggested that MZs exhibited remarkable differences of genome-wide 5-methylcytosine. According to a set of criteria of selection, 92 CpG sites with signi-cant differences of methylation status within MZs were identied from the global epigenome. In conclusion, this pilot study suggested that CpG methylation prole could be a useful biomarker in individual identication of MZs.
Keywords Forensic genetics Individual identication
Monozygotic twins DNA methylation
Introduction
Theoretically, monozygotic twins (MZs) share completely identical genomic DNA sequence, which makes it impossible to distinguish MZs from one another with conventional DNA genetic markers [1, 2], like short tandem repeats (STRs), single nucleotide polymorphisms (SNPs) or Insertion/Deletion polymorphisms (InDels). However, MZs almost always show various degrees of phenotypic discordance [35]. In the last decade, evidences have been accumulating that epigenetic modications of DNA and histones can play a primary role in phenotypic outcomes, including human diseases [610]. Such results provided an unprecedented idea about how to discriminate MZs for forensic purposes. As for the application of forensic genetics, DNA methylation might be one of the most promising epigenetic markers in the discrimination of MZs. Previous studies have showed that there are DNA methylation differences within MZs [6, 7]. Besides, high-performance methods of site-specic or epigenome-wide DNA methylation detection, such as high resolution melting curve (HRM), MethyLight and bead arrays [1113] had been established. In this study, an epigenome-wide scan was employed to identify those potential CpG sites for discrimination of MZs.
Materials and methods
Sample collection
Blood samples were taken from 13 pairs of female and 9 pairs of...