We confirmed this mutational signature within haematopoietic colonies expanded from single cells in a TN-ET (PD6577, Fig.5g) and CALR-mutated (PD63423, Fig.6a, Supplementary Fig.7) patient wherein HC-associated mutations were detectable across every colony (Fig.5g), both mutant and normal haematopoietic lineages, demonstrating that mutagenesis extends beyond tumour clones. Here, CALR is linked to neoplasm.