BCR and neoplasm: Comparing the paediatric population with the population of adults, the BCR::ABL1-neg MPNs are not only much rarer, but also in more than 50% of paediatric patients these neoplasms are triple-negative, i.e., without the JAK2, CALR, or MPL mutations, that drive BCR::ABL1-neg MPNs in the absolute majority of adult patients [6, 7, 9],