Real-time RT-PCR quantification of RUNX1 transcripts in megakaryoblasts from children with and children without DS newly diagnosed with AMkL. Transcript levels for RUNX1a, RUNX1b/1c, and RUNX1c were measured by real-time RT-PCR and normalized to 18S rRNA levels. RUNX1b transcript levels were calculated by subtracting RUNX1c transcript levels from the total transcript levels for RUNX1b/1c. The horizontal lines indicate median RUNX1 transcript levels in each group of patient samples. The P value was determined by the nonparametric Mann-Whitney U test.