title: Developing a DNA methylation assay for human age prediction in blood and bloodstain.
abstract: Age prediction of an individual based on biological traces remained in a crime scene is of ultimate importance for criminal investigation. Growing evidence indicates that some CpG sites may have age-related methylation changes and thus may be a promising tool for age prediction. In this study, we utilized the pyrosequencing approach to screen age-related CpG (AR-CpG) sites for age prediction. Five AR-CpGs were identified as age-related markers from thirty-eight candidates, among which three CpG sites, ITGA2B_1, NPTX2_3, and NPTX2_4 were never reported in previous studies. We fit a linear regression model for age prediction based on methylation assay for 89 blood samples from donors aged 9-75 years old. The model included four AR-CpG markers in three gene fragments ASPA, ITGA2B and NPTX2 and enabled the age prediction with R(2)=0.819. The mean absolute deviation (MAD) from chronological age of the model was 7.870. We validated the linear regression model with a validation set of 40 blood samples, and the prediction MAD was 7.986. There was no statistically significant difference in age prediction between 20 pairs of blood samples and bloodstains. Six pairs of fresh and old bloodstains were analyzed using our assay. The obtained results showed the assay still performed an effective prediction on bloodstains after four-month storage in room conditions. This study indicates that our DNA methylation assay is a reliable and effective method for age prediction for forensic purposes.
authors.affiliation: Institute of Forensic Medicine, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Institute of Forensic Medicine, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yan
authors.affiliation: Clinical and Translational Research Institute, University of California, San Diego. 9500 Gilman Dr., MC 0990, La Jolla, CA 92093-0990, USA.
authors.forename: Jiayi
authors.initials: J
authors.lastname: Hou
authors.affiliation: Institute of Forensic Medicine, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Fu
authors.affiliation: Institute of Forensic Medicine, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China.
authors.forename: Luyao
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Forensic Medicine, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China. Electronic address: profhou@yahoo.com.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Hou
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood* / Q000235:genetics; D015415:Biomarkers / Q000097:blood; D001801:Blood Stains; D002648:Child; D018899:CpG Islands; D004247:DNA / Q000097:blood* / Q000235:genetics; D019175:DNA Methylation; D005260:Female; D053803:Forensic Genetics / Q000379:methods; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017422:Sequence Analysis, DNA / Q000379:methods*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D004247:DNA
keywords: Age prediction; DNA methylation; Forensic science; Human blood; Human bloodstain; Pyrosequencing