IL36RN and acquired polycythemia vera: Overall, recessive IL36RN mutations are associated with increased risk of PP alone, but not PV [57, 65–67]; both phenotypic variance and incomplete penetrance have been observed, supporting the notion that IL36RN mutations are able to induce manifest disease only in the presence of specific environmental factors and/or further genetic defects at a second disease locus [25, 53, 65].