A-165 JAK2V617F Mutation Prevalence in Thrombophilia Profiles: A Regional Laboratory Experience

Abstract Background The somatic JAK2V617F mutation (JAK2) in myeloproliferative neoplasms (MPNs) has been associated with an increased risk of thrombosis. Data are limited on the relationship between JAK2 and unexplained thrombophilia. As such, thrombophilia screening rarely includes JAK2 as a screening test, usually reserved for patients with thrombotic events in specific or unusual locations (e.g., mesenteric venous thrombosis). This study aims to determine the prevalence of JAK2 in patients with unexplained thrombophilia and its potential association in patients with cytosis. Methods Patients who had previously undergone thrombophilia profile including molecular testing with DNA-stored at TriCore Reference Lab during the 2022 calendar year were identified (n=359). 124 patients were sequentially selected to undergo JAK2 testing. All 359 patients were screened to determine the presence of = 1 cytosis: white blood cell, red blood cell, or platelet count above the respective reference range’s upper limit of normal either within one month of thrombophilia screening OR evidence of persistent cytosis. 23 patients had cytosis (11 in the sequential cohort, 11 additional patients with DNA, 1 patient with insufficient DNA). 11 additional patients with cytosis were tested for JAK2. Quantitative RT-PCR results were assigned qualitative values using JAK2 DNA standard clinically validated thresholds: 0%-0.5% negative, 0.5%-1% indeterminate, and > 1% positive. Results Of the 135 samples tested for the JAK2, mean age was 46 (range of 1-86) years, and 103 (76.3%) were female. 1/135 (0.7%) samples was positive for JAK2. The single positive sample (32-year-old male) was within original sequential cohort without cytosis. A Fisher Exact Test shows that there is no correlation with cytosis and JAK2 status (p=1). Conclusion These findings discourage using JAK2 in a first-line thrombophilia genetic screening panel, even in patients with concurrent cytosis. Future directions involve testing additional specimens to increase the sample size of random and cytosis groups. Clinical correlation would also potentially identify a additional associations with which patients could be screened for this testing.