There have revealed multiple mutation hot-spots within SH2 and C-terminal domains in STAT5B, among which N642H has been discovered in various hematological malignancies of T cell origin including T-cell acute lymphoblastic leukemia(T-ALL), T-cell prolymphocytic leukemia(T-PLL), and MEITL [28]. This evidence concerns the gene STAT5B and T-cell prolymphocytic leukemia.