The relative expression of HBB, GATA-1, and DLK-1 is significantly higher in MDS CD34⁺ cells. The relative expression of HBB, GATA-1, and DLK-1 mRNA was measured in freshly isolated CD34⁺ cells (day 0), intermediate phase (day 7, CD36⁺ cells), and late phase (GpA⁺ cells) obtained from 6 RARS, 2 RA, and 13 NBM samples and normalized against 18S rRNA, with NBM as calibrator. Data shown are mean ± SEM. (A) At day 0, the relative expression of HBB was approximately 23-fold higher (P = .001) in low-risk MDS compared with NBM. At days 7 and 14, the relative expression of HBB was higher in MDS compared with NBM (37.6 vs 12.1 and 2089.6 vs 535.5, respectively). However, the fold index was higher in NBM compared with MDS at day 0 (day 7: MDS = 1.4-fold, NBM = 10.4-fold; day 14: MDS = 77-fold, NBM 458-fold). (B) At day 0, the relative expression of GATA-1 was approximately 6-fold higher (P = .001) in low-risk MDS compared with NBM. The relative expression of GATA-1 was lower in MDS compared with NBM at days 7 and 14. (C) The relative expression of DLK-1 was 26-fold and 9.7-fold higher in MDS compared with NBM at days 0 and 7, respectively. There was almost no expression of DLK-1 in GpA⁺ cells in MDS and NBM at day 14.