Analysis of DNA forensic markers using high throughput mass spectrometry

A novel DNA forensics platform has been developed that is based on automated high throughput electrospray ionization mass spectrometry (ESI-MS). The approach uses ESI-MS to "weigh" DNA markers with enough accuracy to yield an unambiguous base composition (A_w, G_x, C_y, T_z) which are then used to derive a DNA profile for an individual. A number of blinded studies have been performed to evaluate the platform for both STR and mtDNA typing. The same platform is used for both analyses and offers advantages over the conventional typing approaches. This approach facilitates the analysis of mtDNA samples containing length heteroplasmy in the HV1/HV2 regions in situations that are not amenable to sequencing. Based on the base compositions profiles from a 24-primer pair assay which covers CRS 15924-16428 and 31-576, this approach is more resolving than traditional sequencing approaches which cover 16024-16365 and 73-340 and facilitates mixture analysis. STR markers can be analyzed in a similar fashion. The high mass accuracy of the measurements affords the ability to detect SNPs within the STR markers. A survey of samples from different population groups suggests that the frequency of SNPs in several of the CODIS loci is in excess of 30%; SNPs were identified in 10 of the 13 core loci.