As discussed above, t-MDS can be subdivided into two groups with different mutational profiles and prognoses: one group characterized by consistent genomic instability with frequent TP53 mutations and numerous cytogenetic abnormalities is associated with a poor prognosis; a second group with lower genomic instability with absent TP53 mutations and a lower number of cytogenetic abnormalities is associated with a prognosis comparable to that of p-MDS. This evidence concerns the gene TP53 and myelodysplastic syndrome.