PCA-based factor analysis of HERVs and embryonic genes in patients with CLL. PCA-based factor analysis (followed by varimax rotation and Kaiser normalization) of HERVs and embryonic genes (HERV-K, HERV-H, SYN-1, pHERV-W, HEMO, OCT4, KLF4, NANOG, and CD133) in HDs (A) and patients with CLL (B). After extracting principal components, those associated with eigenvalues >1 were retained, and individual loadings were extracted through regression methods. Positive/negative loadings (red/blue) indicate a direct/inverse proportionality between the factor and the single biomarker, respectively. Then, the regression values of the principal components from HD (C) and CLL (D) were used to plot and to discriminate CLL (colored dots) from HD populations (white dots). (E) PCA-based factor analysis (followed by varimax rotation and Kaiser normalization) performed in CLL according to treatment regimens.