Besides confirming already known molecularly-defined sub-entities such as MDS with low blast counts and isolated del(5q), the first genomic alteration introduced in MDS classification [19], the 5th WHO edition now includes two additional subtypes with defining genetic abnormalities: MDS with low blast counts and SF3B1 mutation, and MDS with biallelic TP53 inactivation [20]. The gene discussed is TP53; the disease is myelodysplastic syndrome.