Using targeted next generation sequencing (NGS) of 104 cancer‐related genes on 197 MPN patients, approximately 10% of patients had no mutation detectable in any of the genes analyzed and 54% had mutations only in JAK2 V617F or CALR. The remaining 36% had additional mutations detected, other than JAK2 V617F or CALR. Most of these were mutations affecting genes implicated in epigenetic regulation [27]. This evidence concerns the gene CALR and cancer.