There is evidence to suggest that mutation of TP53, resulting in the inactivation of the p53 protein, may be one of the molecular events involved in the clonal progression of the 5q- syndrome to AML.42,55–57 Using deep-sequencing technology, Jädersten et al have demonstrated that small hematopoietic cell subclones with TP53 mutation could be detected at an early disease stage in 18% of patients with MDS with del(5q). Here, TP53 is linked to Down syndrome.