Improving STR typing for low template DNA by abasic-site-mediated semi-linear preamplification

Although progress has been seen for low template DNA (LT-DNA) analysis in the last few years, the obtainment of full short tandem repeat (STR) profiles remains challenging in forensic genetics. Preamplification treatment could help increase the recovery of genetic information in STR typing. In this study, an efficient amplification method was investigated, which shows that the application of the abasic site in a single primer for targets could efficiently delete the primer-binding site of PCR products to achieve semi-linear amplification (abSLA PCR). Further, the position of abasic sites located at 8th to 10th from the 3' end of the primers could facilitate PCR amplification. A significant increase in the recovery of STR loci could be obtained using a 4-plex STR pre-amplification (D8S1179, D21S11, D7S820, and CSF1PO) coupled to Identifiler Plus kit in low template of genomic DNA or single cells. Altogether, the application of abSLA amplification method can facilitate conventional STR typing in LT-DNA analysis.