IDH2^R172 mutations define a unique subgroup of AITL with distinct gene expression. (A) Dendrogram of unsupervised hierarchical clustering of 37 AITL cases with mutational status of IDH2^R172, TET2, and DNMT3A. The branches indicate Pearson's correlation among the samples. Fisher's exact test was performed to determine the significance of the tendency of neighboring cases on the dendrogram to have identical mutation status. (B) Supervised heat map of samples across 1035 genes differentially expressed among IDH2/TET2 double-mutant (n = 12), TET2 single-mutant (n = 18), and wild-type (n = 6) AITL (univariate permutation test, P < .01). The profile on the left shows gene expression in primary CD4⁺ T cells treated with IL-12 for 0, 2, 8, 24, and 48 hours. Each column represents a case. Green and red color scale indicates row z-score. Selected differentially expressed genes are listed at the right side of the profile.