title: [Differences of DNA methylation profiles in monozygotic twins' blood samples].
abstract: OBJECTIVE
  To evaluate the potential usefulness of DNA methylation in individual discrimination of monozygotic twins by investigating the differences of DNA methylation profiles in monozygotic twins' blood samples.
  
  
  METHODS
  Blood samples from 22 pairs of monozygotic twins were obtained with informed consent. Genomic DNA extracts were bisulfite treated followed by detection with Infinium HumanMethylation27 BeadChip Assays(Illumina, USA). Epigenetic distances between each pair of monozygotic twins and each pair of unrelated individuals of same gender were calculated with Euclidean distance algorithms. Distribution of epigenetic distance in monozygotic twin group was statistically compared with that in unrelated individuals.
  
  
  RESULTS
  Difference of epigenetic distance between male and female pairs was not statistically significant in unrelated individual group or in monozygotic twin group (P = 0.0695 and 0.4825, respectively). Epigenetic distance of monozygotic twins was significantly lower than that of unrelated individual pair of same gender (Median: 6.02 vs 7.20, P = 0.0002). However, all the epigenetic distance in monozygotic twin group or in unrelated individuals were significantly higher than 4.00 (P < 0.000 1).
  
  
  CONCLUSIONS
  DNA methylation profiles of monozygotic twin's blood samples were significantly different with each other, which was similar to that in unrelated individuals of same gender. These results indicated that DNA methylation was a useful biomarker in individual discrimination of monozygotic twins.
authors.affiliation: Shanghai Key Laboratory of Forensic Medicine, Institute of Forensic Science, Ministry of Justice, PR China, Shanghai 200063, China. zhaoshuminxl@hotmail.com
authors.forename: Shu-Min
authors.initials: SM
authors.lastname: Zhao
authors.forename: Su-Hua
authors.initials: SH
authors.lastname: Zhang
authors.forename: Jin-Zhong
authors.initials: JZ
authors.lastname: Chen
authors.forename: Shi-Lin
authors.initials: SL
authors.lastname: Li
authors.forename: Cheng-Tao
authors.initials: CT
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D041321:Chromosomes, Human, X / Q000235:genetics; D018899:CpG Islands; D019175:DNA Methylation; D057890:Epigenomics; D005260:Female; D005819:Genetic Markers; D014644:Genetic Variation; D015894:Genome, Human / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D012737:Sex Factors; D014430:Twins, Monozygotic / Q000235:genetics*; D055815:Young Adult
chemical_list: D005819:Genetic Markers