Forensic DNA fingerprinting by liquid chromatography-electrospray ionization mass spectrometry

The determination of the molecular mass of a DNA sequence has several benefits over conventional fragment-length analysis that are advantageous to the forensic field: (i) sequence variation is captured that increases the power of discrimination compared with that obtained by conventional fragment-length analysis. First experiments showed that this increase makes up to 20%-30% for STR analysis. The new technical approach does not invalidate established developments and data, but adds to this information with additional discriminative categories. (ii) ICEMS is faster and cheaper than electrophoresis, does not require internal size standards, allelic ladders, or spectral calibration, which are necessary for fluorescence-based electrophoresis. (iii) ICEMS can unequivocally detect any single sequence variation in DNA molecules with lengths up to 250 nucleotides. This allows for maximum discrimination of forensically relevant DNA fragments, covering all sorts of STRs, SNPs, and also the analysis of the hypervariable segments of mtDNA. More effort, however, needs to be put into software development that escorts the analysis and data interpretation processes to make this technology manageable for the practical user.