TP53 and myelodysplastic syndrome: Thus, in the 2022 WHO classification, MDS with biallelic TP53 inactivation (MDS-biTP53), which means the presence of two or more TP53 mutations or of one mutation, with evidence of TP53 copy number loss or copy neutral loss of heterozygosity (LOH), when BM or peripheral blood blasts are less than 20% constitutes a new clinical entity.