The JAK-2 V617F mutation which can be easily found in myeloproliferative neoplasm has been reported in a small part of MDS and its prognostic significance is unclear.[44,45] U2AF1 mutations occurred probably more frequently in patients with isolated -20/20q- or trisomy 8 than the others.[20,21,27] It was suggested that U2AF1 mutation was an independent prognostic factor for OS in MDS patients (<50 years).[21] It was also shown that patients with U2AF1 mutations were more likely to progress to AML.[20] In our study, U2AF1 mutations showed significant disadvantage in OS and LFS in MDS patients. This evidence concerns the gene JAK2 and acute myeloid leukemia.