DNA methylation-based semen age prediction using the markers identified in Koreans and Europeans

In the forensic field, sexual assaults have consistently been the important issue, with semen frequently serving as the primary evidence. When the suspect is unidentified, estimating the perpetrator's age using investigating semen can provide important information. The VISAGE consortium conducted research on the semen age prediction focused on European semen samples, but the age prediction model has remained undisclosed. Additionally, several studies have reported methylation differences across populations, indicating that the European semen age prediction model might not be broadly applicable to other groups. A study did explore semen age prediction in Koreans using Illumina's Infinium Methylation450K BeadChip array, however recent developments in technology could enhance this approach. To address this, we conducted a study on Korean males aged 18-70 years. We initially analyzed 49 samples utilizing Illumina's Infinium MethylationEPIC BeadChip array to identify age-related CpG sites. From this analysis, we identified 9 age-related CpG markers, excluding one due to difficulties in locus-specific analysis. As a result, we used 11 markers including 8 newly identified CpGs from the EPIC array and 3 CpG markers from previous research utilizing the SNaPshot assay. Furthermore, we incorporated 13 CpG markers from the European study to analyze a total of 159 semen samples using the Illumina Nextera MPS system. This approach enabled us to test age-related markers identified in Europeans within the Korean population and to construct a more accurate age prediction model using markers from both Korean and European sources.