The continuum model for V617F-positive thrombocythemia and polycythemia.

The phenotypic consequences of the V617F mutation, and hence the position of any individual within the continuum, will depend on physiological and genetic modifiers. Erythropoiesis is constrained by iron deficiency and low serum erythropoietin, but is promoted by male gender and V617F-homozygosity. Other acquired and inherited modifiers are also likely to affect the phenotype. The position of the arrows is not meant to denote the relative strength of the various modifiers.