Evolution of the clonality ratio in 3 patients with skewed XIP before ABMT, who subsequently developed t-MDS/AML. The progressive and significant increase of the clonality ratio, detected in serial analysis in patient no. 29 (A) and in patient no. 23 (B), attest to the clonal evolution. In contrast, no significant change is detected in the clonality ratio of patient no. 2 (C), despite development of t-MDS/AML 36 months after ABMT.