Predicting human age by detecting DNA methylation status in hair

Abstract

Age prediction is of great importance for criminal investigation and judicial expertise. DNA methylation status is considered a promising method to infer tissue age by virtue of age‐dependent changes on methylation sites. In recent years, forensic scientists have established various models to predict the chronological age of blood, saliva, and semen based on DNA methylation status. However, hair‐inferred age has not been studied in the field of forensic science. In this study, we measured the methylation statuses of potential age‐related CpG sites by using the multiplex methylation SNaPshot method. A total of 10 CpG sites from the LAG3, SCGN, ELOVL2, KLF14, C1orf132, SLC12A5, GRIA2, and PDE4C genes were found to be tightly associated with age in hair follicles. A correlation coefficient above 0.7 was found for four CpG sites (cg24724428 and Chr6:11044628 in ELOVL2, cg25148589 in GRIA2, and cg07547549 in SLC12A5). Among four age‐prediction models, the multiple linear regression model consisting of 10 CpG sites provided the best‐fitting results, with a median absolute deviation of 3.68 years. It is feasible to obtain both human identification and age information from a single scalp hair follicle. No significant differences in methylation degree were found between different sexes, hair types, or hair colors. In conclusion, we established a method to evaluate chronological age by assessing DNA methylation status in hair follicles.

Age determination through DNA methylation patterns of fingernails and toenails

“…Using hair as sample material, Hao et al . reported a median absolute deviation of 4.15 – 6.38 years for their test set, depending on the method of variable selection [38]. These results are comparable with those acquired from the current study.…”

“…The aim of these studies was to assess the reliability and specificity of the differentially methylated parental allele method in several human tissues, including fingernails. In addition, one publication of an age prediction model was based on DNAm patterns in hair, where a median absolute deviation of 4.15 years and RMSE of 4.92 years were obtained for a Chinese study population[38]. Considering the resemblance between of nails and hair in terms of biogenesis, and thus micro-structural components, these results are promising for age prediction based on DNAm patterns in nails.…”

Age estimation based on blood DNA methylation levels in brown bears

“…As far as we know, age-related changes in expression at the mRNA or protein levels have never been reported. In humans, the DNA methylation level of the CpG site proximal to this gene is a frequently used target for age estimation in a variety of samples, including blood, saliva, buccal swabs, and hair (Florath et al 2014;Hong et al 2017;Hao et al 2021;Schwender et al 2021). This finding suggests that agedependent methylation changes at CpG sites adjacent to SLC12A5 occur in a tissue-independent manner.…”

Age estimation based on blood DNA methylation levels in brown bears

“…As far as we know, age‐related changes in expression at the mRNA or protein levels have never been reported. In humans, the DNA methylation level of the CpG site proximal to this gene is a frequently used target for age estimation in a variety of samples, including blood, saliva, buccal swabs, and hair (Florath et al, 2014; Hao et al, 2021; Hong et al, 2017; Schwender et al, 2021). This finding suggests that age‐dependent methylation changes at CpG sites adjacent to SLC12A5 occur in a tissue‐independent manner.…”