Abstract
BackgroundIn addition to the DNA sequence, epigenetic markers have become substantial forensic tools during the last decade. Estimating the age of an individual from human biological remains may provide information for a forensic investigation. Age estimation in molecular strategies can be obtained by telomere length, mRNa mutation, or by sjTRECs but the accuracy is not sufficient in forensic practice because of high margin error.Main bodyOne solution to this problem is to use DNA methylation methods. DNA methylation markers for tissue identification at age-associated CpG sites have been suggested as the most informative biomarkers for estimating the age of an unknown donor. This review aims to give an overview of DNA methylation profiling for estimating the age in cases of forensic relevance and the important aspects in determining the mean absolute deviation (MAD) or mean absolute error (MAE) of the estimated age. Online database searching was performed through PubMed, Scopus, and Google Scholar with keywords selected for forensic age estimation. Thirty-two studies were included in the review, with variable DNA samples but blood commonly as a source. Pyrosequencing and EpiTYPER were methods mostly used in DNA analysis. The MAD in the estimates from DNA methylation was about 3 to 5 years, which was better than other methods such as those based on telomere length or signal-joint T-cell receptor excision circles. The ELOVL2 gene was a commonly used DNA methylation marker in age estimation.ConclusionDNA methylation is a favorable candidate for estimating the age at the time of death in forensic profiling, with an uncertainty mean absolute deviation of about 3 to 5 years in the predicted age. The sample type, platform techniques used, and methods to construct age predictive models were important in determining the accuracy in mean absolute deviation or mean absolute error. The DNA methylation outcome suggests good potential to support conventional STR profiling in forensic cases.
Highlights
The online literature search in the Scopus, Google Scholar, and Pubmed/Medline databases was applied to define keywords of “age estimation” OR “age determination” AND “Deoxyribonucleic acid (DNA) methylation” AND “forensic”
Data extraction The studies comparing the different methods of forensic age estimation were extracted as follows: name of the first author, year of publication, methods, source of samples, number of samples, age, age prediction as mean absolute deviation (MAD) and RSME/Standard error of the estimate (SEE) (Table 1)
DNA methylation is a favorable candidate in estimating the age at the time of death in forensic profiling
Summary
Methods The online literature search in the Scopus, Google Scholar, and Pubmed/Medline databases was applied to define keywords of “age estimation” OR “age determination” AND “DNA methylation” AND “forensic”. The inclusion criteria were studies describing the DNA methylation analysis for age estimation combined with or without other methods, with no restriction of sample size or age ranges, but restricted to reporting in the English language, publication within 2014–2019, and topics related to forensic studies. The exclusion criteria were satisfied by review studies, age estimation without molecular analysis, and abstracts without full paper available. This review aims to give an overview of DNA methylation profiling for estimating the age in cases of forensic relevance and the important aspects in determining the mean absolute deviation (MAD) or mean absolute error (MAE) of the estimated age. Online database searching was performed through PubMed, Scopus, and Google Scholar with keywords selected for forensic age estimation. The ELOVL2 gene was a commonly used DNA methylation marker in age estimation. Epigenetics can be affected by environmental exposure, such as diet and smoking (Lee and Pausova 2013)
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