Forensic Application of DNA Methylation in Age- Prediction

DNA methylation defined as the addition of methyl group to the 5’ cytosine of CG dinucleotide (CpGs). As CpG sites across wide range of aging research found to be highly associated with age, multiple age predictive models using DNA methylation at CpG site have been made. DNA methylation considered the most accurate method for age prediction [1]. Variable DNA methylation can be determined by cell differentiation, aging as well as environmental exposure. The established DNA methylation pattern during early years of development are maintained and remain relatively stable throughout life, decrease or increase in different loci [2]. Age-related methylation changes throughout the life of an individual concluded in two phenomena: the epigenetic clock and epigenetic drift. Epigenetic in general is defined as the modification of DNA and DNA packaging without any change in DNA sequence. Epigenetic clock is the age associated DNA methylation changes that are common across individuals of the same age. However, epigenetic drift is the accumulation of small changes or errors that is determined by the environment in which the person ages and it influences [3,4]. In epigenetic more specific age-associated DNA methylation changes at certain loci or genes were easier to be detected by the emergence of microarray and massive parallel sequencing technologies (MPS). Although age prediction using DNA methylation is not quite parallel to the chronological age [4]. DNA methylation measures at multiple CpG sites provide close prediction of a chronological age, with a narrow range that varies and specify the accuracy of each method introduced. Thereby, choosing the most appropriate analytical method for forensic application is more difficult than in clinical application. This review will improve the understandings about DNA methylation markers and their potential to be used as biomarkers in the forensic field, with a future plan to apply the previously identified markers on different tissues and test accuracy as well as identify more DNA methylation markers for various tissues, blood and semen.