CALR and myeloproliferative neoplasm: Since 2005, some scholars first discovered that the mutation rate of the JAK2V617F gene in BCR/ABL-negative MPN was greater than 50% [2]; in the following decade, mutations occurring in MPLW515, exon 12 of JAK2, and exon 9 of CALR were successively identified and reported [3,4,5].