Mutations in TP53, encoding p53, are not common in AML/MDS patients and represent 5–20% de novo cases, however the proportion is increased in the older patients, in AML transformed from MDS, in cases carrying del(5q) or complex karyotypes or in the therapy-induced AML (chemotherapy/irradiation) [105,125]. The gene discussed is TP53; the disease is acute myeloid leukemia.