SF3B1 and myelodysplastic syndrome: Myelodysplastic neoplasms with defining genetic abnormalities are grouped together and include: MDS with low blasts and isolated 5q deletion (MDS-5q), MDS with low blasts and SF3B1 mutation (MDS-SF3B1), and MDS with biallelic TP53 inactivation (MDS-biTP53).