Clonal Hematopoiesis and Blood-Cancer Risk

To the Editor: Genovese et al. (Dec. 25 issue)1 report that activating mutations in FLT3 were not observed in participants with subclinical clonal expansions. We note from the Supplementary Appendix, available with the full text of the article at NEJM.org, that the variant-calling algorithm used in their study was the Genome Analysis Toolkit (GATK). It has been reported by others that internal tandem duplications (ITDs) in FLT3 are not detected by the GATK2 and that Pindel appears to be a better algorithm.2,3 We wonder whether ITDs in FLT3 might be detected in the data set of Genovese et al. if a different algorithm is used.