The 46/1 (JAK2 GGCC) haplotype and single-nucleotide polymorphisms (SNP) in JAK2, in the telomerase reverse transcriptase (TERT), in the MDS1 and EVI1 complex locus (MECOM), or in HBS1L-MYB have been reported to be associated with a predisposition to mutation in the JAK2 gene on the same allele (JAK2 GGCC haplotype) or a predisposition to the development of a MPN (MECOM, TERT, JAK2, and HBS1L-MYB variants) [90–94]. The gene discussed is JAK2; the disease is myeloproliferative neoplasm.