The age-related expression decline of ERCC1 and XPF for forensic age estimation: A preliminary study

The age-related capacity decline of DNA damage repair in human peripheral blood has been demonstrated. Excision repair cross-complementation group1 (ERCC1) and Xeroderma pigmentosum complementation group F (XPF) were rate-limiting enzyme in nucleotide excision repair (NER) which was known as the most important DNA damage repair system. Consequently, we hypothesized that the expression and/or activity of ERCC1 and XPF may be associated with age. However, little was known about the quantitative relationship of ERCC1 and XPF expression levels with age. The aim of the present study was to analyze the correlation of ERCC1 and XPF expression levels with age by detecting the ERCC1 and XPF mRNA levels in peripheral blood mononuclear cells(PBMCs) and protein levels in plasma in healthy ethnic Han Chinese individuals, and finally find new molecular markers for forensic age estimation by establishing the mathematical model between ERCC1 and XPF expression levels and age. The results showed that the ERCC1 and XPF mRNA relative expression levels in PBMCs declined in an age-dependent manner (r = -0.578/-0.844, respectively, P < 0.01). The formula for age estimation based on the ERCC1 and XPF mRNA relative expression levels decline in PBMCs were Y = 3.3E-5x²-0.0261x+1.9175 (R² = 0.3244, P < 0.01) and Y = 0.0003x²-0.0459x+2.0439 (R² = 0.729, P < 0.01), respectively. There were no significant differences of the ERCC1 or XPF protein expression levels in plasma between age groups (P > 0.05). Furthermore, there were no significant differences of the ERCC1 or XPF mRNA and/or protein expression levels between males and females(P > 0.05). It suggested that the ERCC1 and XPF mRNA expression levels could be considered as valuable additional tool in individual age estimation, especially in cases where traditional morphologic method was inefficient or absent in forensic practice.