Allele typing of short tandem repeats by capillary electrophoresis

Capillary electrophoresis with laser-induced fluorescence was applied to th e analysis of six STRs and the amelogenin sex test with the purpose of veri fying accuracy and precision of the sizing method with the GS500 internal s tandard. Sequenced dye-labeled, PCR-amplified alleles from amelogenin, HumV WA31, HumTH01, HumF13A01, HumFIBRA, D21S11 and HumCSF1PO loci were run seve ral times on the same capillary and on multiple capillaries and the offset of computer-measured fragment sizes from the expected molecular weights was calculated and analysed. All loci except D21S11 showed a poor degree of ac curacy. Precision results from run-to-run and day-to-day injections display ed a maximum standard deviation (SD) > 0.15 nt for HumVWA31, HumF13A01, D21 S11 and HumFIBRA, although the maximum range of calculated sizes in multipl e runs was lower than 1 basepair. No variation in precision was observed ac cording to the quality of the DNA template. Allele typing by comparison wit h allelic ladders for each locus is recommended.