The prevalence of the activating JAK2 tyrosine kinase mutation in chronic porto-splenomesenteric venous thrombosis

P>Background Occult myeloproliferative disorders (MPD) are present in 25% of patients with chronic portal, splenic and mesenteric venous thrombosis (PSMVT). A somatic mutation of JAK2 (JAK2V617F) can be used to identify patients with latent MPD. Aim We evaluated the prevalence and clinical significance of JAK2V617F in patients with chronic PSMVT. Methods Allele-specific polymerase chain reaction was performed to screen for JAK2V617F. Results Thirty-five patients were tested for JAK2V617F. The underlying pro-coagulant condition was MPD in seven of 35 (20.0%) patients; other aetiologies included hereditary thrombophilia (n = 5), chronic pancreatitis (n = 2), liver abscess (n = 1) and umbilical vein sepsis (n = 3). The remainder were labelled idiopathic, i.e. 17/35 (48.6%) patients. JAK2V617F was detected in 16/35 (45.7%) patients: seven of seven (100%) with MPD, two of 11 (18.1%) with non-MPD acquired conditions and seven of 17 (41.2%) with 'idiopathic' chronic PSMVT. Mean haemoglobin concentration (P = 0.04), haematocrit (P = 0.04), white cell count (P = 0.002) and platelet count (P = 0.05) were significantly higher in patients with JAK2V617F. None of the seven patients with latent MPD have progressed to overt MPD over median follow-up of 85 months. Conclusion JAK2V617F occurs in 41% of patients with idiopathic chronic portal, splenic and mesenteric venous thrombosis, confirming the presence of latent myeloproliferative disorders, and should form part of the routine pro-coagulant screen.