While the STATH, ALAS2, and HTN3 markers were detected in semen, the average expression level for these genes was less than 145 RFUs (Fig. 2B). Menstrual blood and vaginal secretion markers showed the highest level of cross-reactivity with the semen stains, although their average expression was less than 4% of the average peak heights of PRM2 and TGM4 (Fig. 2B). The differences in the average peak height among the semen-specific markers and MMP7 and MUC4 were statistically significant (MMP7: p = 2.3 1025 for PRM2 and p = 8.3 1037 for TGM4; MUC4: p = 1.7 1025 for
PRM2 and p = 8.7 1037 for TGM4).