JAK2Negative Erythrocytosis Associated with JAK2GGCC_46/1 Haplotype, Calrrs1049481_G, and Normal Erythropoietin Level: Is This a New Entity?

Introduction.The JAK2haplotype known as “GGCC or 46/1 haplotype” consists of a germline combination of single nucleotide polymorphisms (SNPs) that are inherited together and are frequently associated with the onset of myeloproliferative neoplasms (MPNs) positive for both JAK2V617 and exon 12 mutations. It has been reported a significant association between JAK2negative erythrocytosis and the simultaneous occurrence of JAK2haplotype GGCC_46/1 and CALRrs1049481_G allele, mapping in the 3' UTR of the gene. In the present study, we investigated the presence of JAK2haplotype GGCC_46/1 and CALRrs1049481_G allele in a more extensive series of erythrocytosis patients and evaluated a possible correlation with serum erythropoietin (EPO) level.