Comparison of STR-PCR and real-time PCR assays.

Eleven artificial cell mixtures, containing decreasing proportions of recipient cells in donor cells, were constructed. DNA extracted from these cell mixtures was evaluated by both fluorescent-based STR-PCR assay (with the 2 informative Tho1 and D21S11 markers) and real-time PCR assay (with the 3 recipient-specific markers S 08b, S 09a, and S 11a). In the STR-PCR results (A), recipient genotypes were detected until the 5% and 2.5% recipient cell fraction with D21S11 and Tho1 STR markers, respectively. In addition, these 2 STRs evidenced diverging results as the recipient genotype fraction decreased. In the real-time PCR assay (B), recipient genotypes were detected and properly quantified until 0.07% recipient cell fraction, regardless of the allelic marker used.