Representative cases with MBR1, mcr1, and mcr2 breakpoints detected by Δ-PCR. DNA (20 ng) extracted from cases 36 (A), 19 (B), and 30 (C) and from a case with lymphoid hyperplasia (D) was subjected to multiplex Δ-PCR and analyzed by capillary electrophoresis with 45-second electrokinetic injection. Cases 36, 19, and 30 were positive for MBR1 (Δ18 ± 1 bp), mcr1 (Δ39 ± 1 bp), and mcr2 (Δ33 ± 1 bp), respectively, based on the size difference of the two amplicon peaks.