Although SH2 and TAD domains are the known mutation hotspot area in the STAT5B gene, we also identified novel variants in the CCD (Q220H) and DBD (E433K/G) of STAT5B. Similarly, the majority of the STAT3 mutations are in the SH2 domain in CD8+ T-LGLL but additional mutations are also found in other domains [4] underlining the importance of covering all mutation hotspots in the diagnostic tests of LGLL. This evidence concerns the gene STAT3 and T-cell large granular lymphocyte leukemia.