Within the subset of donors for whom a paired, cryopreserved PBMC sample was available [18 controls (4 females), 16 PV (2 females)], higher CRP levels were noted in PV [1.9 (0.6–2.8) vs. 0.6 (0.3–1) mg/l, P=0.021], with no difference in sex composition (P=0.608) (P=0.66, Fisher’s exact test), age (P=0.628), CMV IgG titre (P=0.608), and BMI (P=0.138) between the case-control groups. The gene discussed is CRP; the disease is acquired polycythemia vera.