Kaplan-Meier analysis of survival of PMF patients stratified according to their genotype, as it was known in different time periods. (A) OS of the whole population of PMF patients: the genetic basis of MPNs was unknown before 2005, and therefore no genotypic subgroup could be defined. (B) PMF patients stratified according to JAK2 or MPL mutation status: these mutant genes where identified in 2005 and 2006, respectively. (C) PMF patients stratified according to JAK2, CALR, or MPL mutation status: somatic mutations of calreticulin were identified in 2013.