JAK2 and leukemia: In particular, an activating point mutation in JAK2 (JAK2V617F) has been described with high frequency in chronic myeloproliferative disorders (MPD) [5], [6], [7], [8], [9], [10] and constitutive JAK2 activation caused by chromosomal translocations has been reported in various types of leukemia [11], [12], [13].