title: LINE-1 DNA methylation: A potential forensic marker for discriminating monozygotic twins.
abstract: Discriminating individuals within a pair of monozygotic (MZ) twins using genetic markers remains unresolved. This inability causes problems in criminal or paternity cases involving MZ twins as suspects or alleged fathers. Our previous study showed DNA methylation differences in interspersed repeat sequences such as Alu and LINE-1 within pairs of newborn MZ twins. To further evaluate the possible value of LINE-1 DNA methylation for discriminating MZ twins, this study investigated the LINE-1 DNA methylation of a large number of twins. We collected blood samples and buccal cell samples from 119 pairs of MZ and 57 pairs of dizygotic (DZ) twins. Genomic DNA was extracted and LINE-1 methylation level was detected using bisulfite pyrosequencing. The mean methylation level of the three CpG sites in the blood sample among the 176 unrelated individuals was 76.60% and 70.08% in buccal samples. This difference was significant, indicating the tissue specificity of LINE-1 DNA methylation. Among 119 pairs of MZ twins, 15 pairs could be discriminated according to the difference of CpG methylation level between them, which accounted for 12.61% of total number of MZ pairs. As for DZ twins, 10 pairs had significant differences between two individuals, which accounted for 17.54% of the total 57 DZ pairs. In conclusion, there are global DNA methylation differences within some healthy concordant monozygotic (MZ) twin pairs. LINE-1 DNA methylation might be a potential marker for helping to discriminate individuals within MZ twin pairs, and the tissue specificity must be considered in practice.
authors.affiliation: Hebei Key Laboratory of Forensic Medicine, Department of Forensic Medicine, Hebei Medical University, No. 361 Zhong Shan Road, Shijiazhuang, Hebei 050017, PR China.
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.affiliation: Hebei Key Laboratory of Forensic Medicine, Department of Forensic Medicine, Hebei Medical University, No. 361 Zhong Shan Road, Shijiazhuang, Hebei 050017, PR China.
authors.forename: Guangping
authors.initials: G
authors.lastname: Fu
authors.affiliation: Epidemiology and Health Statistics Department, School of Public Health, Hebei Medical University, PR China.
authors.forename: Lina
authors.initials: L
authors.lastname: Yan
authors.affiliation: Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Jeffery M
authors.initials: JM
authors.lastname: Craig
authors.affiliation: Hebei Key Laboratory of Forensic Medicine, Department of Forensic Medicine, Hebei Medical University, No. 361 Zhong Shan Road, Shijiazhuang, Hebei 050017, PR China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Hebei Key Laboratory of Forensic Medicine, Department of Forensic Medicine, Hebei Medical University, No. 361 Zhong Shan Road, Shijiazhuang, Hebei 050017, PR China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Fu
authors.affiliation: Hebei Key Laboratory of Forensic Medicine, Department of Forensic Medicine, Hebei Medical University, No. 361 Zhong Shan Road, Shijiazhuang, Hebei 050017, PR China.
authors.forename: Chunling
authors.initials: C
authors.lastname: Ma
authors.affiliation: Hebei Key Laboratory of Forensic Medicine, Department of Forensic Medicine, Hebei Medical University, No. 361 Zhong Shan Road, Shijiazhuang, Hebei 050017, PR China. Electronic address: shujinli@163.com.
authors.forename: Shujin
authors.initials: S
authors.lastname: Li
authors.affiliation: Hebei Key Laboratory of Forensic Medicine, Department of Forensic Medicine, Hebei Medical University, No. 361 Zhong Shan Road, Shijiazhuang, Hebei 050017, PR China. Electronic address: hbydcongbin@126.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Cong
mesh_terms: D002681:China; D018899:CpG Islands; D019175:DNA Methylation; D005006:Ethnicity / Q000235:genetics; D005260:Female; D053803:Forensic Genetics; D005819:Genetic Markers; D006801:Humans; D007231:Infant, Newborn; D020084:Long Interspersed Nucleotide Elements; D008297:Male; D014430:Twins, Monozygotic
chemical_list: D005819:Genetic Markers
keywords: Bisulphite conversion; DNA methylation; Epigenetics; LINE-1; Monozygotic twins; Pyrosequencing