After performing globin reduction on PAXgene Blood RNA, do I get an equivalent expression profile to the same sample when starting with RNA isolated using an erythrocyte lysis method?
No. The resulting blood cell fraction obtained using an RNA isolation method that includes erythrocyte lysis overlaps only in part with the cell population represented in RNA isolated from whole blood. The globin reduction procedure is designed to improve GeneChip®assay sensitivity by eliminating amplification and labeling of the very abundant globin transcripts found in red blood cells. However, although these transcripts are present at high levels, they constitute only a very small number of the total different transcripts contributed to the sample by this cell population. Therefore, even after globin reduction, RNA isolated from whole blood has additional transcripts not found in RNA isolated by erythrocyte lysis thereby resulting in differences in the expression profiles obtained using these different methods. For more detailed information on cell fractions represented following different blood collection or RNA isolation methods, please refer to the technical note entitled "Globin Reduction Protocol: An analysis of blood processing methods to prepare samples for GeneChip expression profiling".