title: Examination of DNA methylation status of the ELOVL2 marker may be useful for human age prediction in forensic science.
abstract: Age estimation in forensic investigations may complement the prediction of externally visible characteristics and the inference of biogeographical ancestry, thus allowing a better description of an unknown individual. Multiple CpG sites that show linear correlation between age and degree of DNA methylation have been identified in the human genome, providing a selection of candidates for age prediction. In this study, we optimized an assay based on bisulfite conversion and pyrosequencing of 7 CpG sites located in the ELOVL2 gene. Examination of 303 blood samples collected from individuals aged 2-75 years allowed selection of the most informative site, explaining 83% of variation in age. The final linear regression model included two CpG sites in ELOVL2 and enabled age prediction with R(2)=0.859, prediction error=6.85 and mean absolute deviation MAD=5.03. Examination of a testing set of 124 blood samples (MAD=5.75) showed that 68.5% of samples were correctly predicted, assuming that chronological and predicted ages matched ± 7 years. It was found that the ELOVL2 methylation status in bloodstains had not changed significantly after 4 weeks of storage in room temperature conditions. Analysis of 45 bloodstains deposited on tissue paper after 5, 10 and 15 years of storage in room conditions indicated that although a gradual decrease of positive PCR results was observed, the general age prediction success rate remained similar and equaled 60-78%. The obtained results show that the ELOVL2 locus provides a very good source of information about human chronological age based on analysis of blood, including bloodstains, and it may constitute a powerful and reliable predictor in future forensic age estimation models.
authors.affiliation: Central Forensic Laboratory of the Police, Aleje Ujazdowskie 7, 00-583 Warsaw, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Zbieć-Piekarska
authors.affiliation: Central Forensic Laboratory of the Police, Aleje Ujazdowskie 7, 00-583 Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Spólnicka
authors.affiliation: Institute of Forensic Research, Westerplatte 9, 31-033 Krakow, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Kupiec
authors.affiliation: Central Forensic Laboratory of the Police, Aleje Ujazdowskie 7, 00-583 Warsaw, Poland.
authors.forename: Żanetta
authors.initials: Ż
authors.lastname: Makowska
authors.affiliation: Central Forensic Laboratory of the Police, Aleje Ujazdowskie 7, 00-583 Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Spas
authors.affiliation: Institute of Forensic Research, Westerplatte 9, 31-033 Krakow, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Parys-Proszek
authors.affiliation: BioVectis, Pawińskiego 5a/d, 02-106 Warsaw, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kucharczyk
authors.affiliation: Medical University of Warsaw, Żwirki i Wigury 61, 02-091 Warsaw, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Płoski
authors.affiliation: Institute of Forensic Research, Westerplatte 9, 31-033 Krakow, Poland. Electronic address: wbranicki@ies.krakow.pl.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Branicki
mesh_terms: D000123:Acetyltransferases / Q000235:genetics*; D018899:CpG Islands; D019175:DNA Methylation; D000081031:Fatty Acid Elongases; D053803:Forensic Genetics; D005819:Genetic Markers; D006801:Humans
chemical_list: C000630967:ELOVL2 protein, human; D005819:Genetic Markers; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases
keywords: Age prediction; Biomarker; CpG islands; DNA methylation; ELOVL2; Forensic science