Table 3.

Classification and defining features of myelodysplastic neoplasms (MDS).

	Blasts	Cytogenetics	Mutations
MDS with defining genetic abnormalities
MDS with low blasts and isolated 5q deletion (MDS-5q)	<5% BM and <2% PB	5q deletion alone, or with 1 other abnormality other than monosomy 7 or 7q deletion
MDS with low blasts and SF3B1 mutationa (MDS-SF3B1)		Absence of 5q deletion, monosomy 7, or complex karyotype	SF3B1
MDS with biallelic TP53 inactivation (MDS-biTP53)	<20% BM and PB	Usually complex	Two or more TP53 mutations, or 1 mutation with evidence of TP53 copy number loss or cnLOH
MDS, morphologically defined
MDS with low blasts (MDS-LB)	<5% BM and <2% PB
MDS, hypoplasticb (MDS-h)
MDS with increased blasts (MDS-IB)
MDS-IB1	5–9% BM or 2–4% PB
MDS-IB2	10-19% BM or 5–19% PB or Auer rods
MDS with fibrosis (MDS-f)	5–19% BM; 2–19% PB

^aDetection of ≥15% ring sideroblasts may substitute for SF3B1 mutation. Acceptable related terminology: MDS with low blasts and ring sideroblasts.

^bBy definition, ≤25% bone marrow cellularity, age adjusted.

BM bone marrow, PB peripheral blood, cnLOH copy neutral loss of heterozygosity.