GATA-1 mRNA expression in patients' hematopoietic cells. Semiquantification of GATA-1 gene expression was performed after coamplification and normalization with an internal control β2-microglobulin. RT-PCR products were analyzed by 7% polyacrylamide gel electrophoresis and visualized by BET staining. The GATA-1–β2-microglobulin ratio (401 bp:274 bp) (A) and the FOG-1–β2-microglobulin ratio (275 bp:165 bp) (B) were calculated for patients' CD34⁺ cells (•), compared with CD34⁺ cells from healthy individual bone marrow (▴) and CD34⁺ cells from healthy subject peripheral blood (▪). The results were expressed as curves of cumulative frequencies, the y-axis corresponding to the GATA-1–β2-microglobulin ratio or FOG1–β2-microglobulin ratio, and the x-axis indicating the percentage of individuals.