JAK2 and acute myeloid leukemia: Since cytogenetic abnormality was not detected in approximately half of AML cases, pathogenesis is explained by gene mutations.3 Mutations classified as class 1 mutations; FLT3, KRAS, NRAS, CKİT, and JAK2 (signaling and kinase pathway), cause increased tyrosine kinase activity, triggering proliferation of the cell.