Comparison of gene expression levels by real-time RT-PCR and GeneChip. The fold difference expression of each target gene relative to an internal control gene (β-actin) was studied using the 2^-ΔΔCT method. The fold changes of gene expression in 10 genes were assessed in CD34 cells obtained from 4 monosomy 7 and 4 trisomy 8 MDS patients. The average fold change of gene expression level from those monosomy 7 (□) and trisomy 8 (▪) patients was calculated as fold change compared with healthy control by both real-time RT-PCR (A) and microarray assay (B). Real-time PCR data were highly correlated to the GeneChip data by linear regression analysis (r = 0.67; P < .016). Similar gene expression patterns of CD34 cells were found in individual with monosomy 7 (○) or trisomy 8 (•) patients (C).