Figure 1.

Distinct expression pattern of HIF2A PGLs. (A) Principal component analysis showed that HIF2A PGLs are clearly distinguishable from other pseudohypoxic PGLs based on their expression pattern. (B) Hierarchical clustering of all pseudohypoxic PGLs based on differentially expressed genes observed by significance analysis of microarray showed separate subclustering of HIF2A PGLs in the previously described cluster-1A (a mixed cluster of SDHB and SDHD-AT PGLs). (C) Top three genes, which allow correct classification of HIF2A PGLs with an excellent error rate of merely 2%. The y-axis indicates relative gene expression to normal adrenal medulla. Median, first, and third quartiles of relative expression z-scores of the gene in question are indicated by midline, bottom, and top of the boxes. Whiskers indicate lowest and highest expression values within 1.5 interquartile ranges of the lower and upper quartile, respectively. Extreme values are depicted as dots and may be considered outliers.