Single-cell sorting, amplification, and mutation scoring. (A) Representative isotype IgG (negative control) and CD34 stainings for patient UPN21. (B) Single-cell 2-step PCR results. Lanes 1-6, DNA from single cells as the template. Lane 7, negative control. (C) Different levels of heteroplasmy of mtDNA mutations at sites 16150 and 189 (arrows) in single cells from leukemia patients DC and UPN17, respectively.