A Rational Approach to JAK2 Mutation Testing in Patients with Elevated Hemoglobin: Results from the JAK2 Prediction Cohort (JAKPOT) Study

Challenges in Diagnosing Polycythemia Vera in Primary Care: A 55-Year-Old Malaysian Woman with Atypical Presentation

BACKGROUND Polycythemia vera (PV) is a myeloproliferative neoplasm (MPNs) marked by elevated hemoglobin and hematocrit, which can lead to thromboembolic events and progress to myelofibrosis or acute myeloid leukemia (AML). MPNs, including PV, are relatively rare in Malaysia, and there is currently no recent published data reporting the demographics and outcomes of PV patients in the country. In Western countries, routine annual blood tests are standard, whereas this practice is less common in Malaysia, underscoring the need for improved awareness and accessibility to ensure timely diagnosis of PV. CASE REPORT This report presents a case of a 55-year-old Malaysian woman in a primary care setting, initially misdiagnosed with benign conditions due to atypical presentations of recurrent bilateral eye redness and dizziness. Persistent symptoms led to further evaluation by primary care and hematologist, which revealed elevated hemoglobin, hematocrit, leukocytosis, JAK2 V617F mutation, and low serum erythropoietin levels, confirming PV, even without proceeding with a bone marrow biopsy. Treatment with phlebotomy, hydroxyurea, and aspirin resulted in significant improvements in ocular symptoms and hematological parameters within 60 days. CONCLUSIONS This case underscores the critical role of primary care in the early detection of polycythemia vera. Timely identification and appropriate referral from primary care settings are essential to avoid diagnostic delays and ensure effective management, improving patient outcomes and preventing complications.

JAKCalc: A machine-learning approach to rationalized JAK2 testing in patients with elevated hemoglobin levels

The demand for Janus Kinase-2 (JAK2) testing has been disproportionate to the low yield of positive results, which highlights the need for more discerning test strategies. The aim of this study is to introduce an artificial intelligence application as a more rational approach for testing JAK2 mutations in cases of erythrocytosis. Test results were sourced from samples sent to a tertiary hospital's genetic laboratory between 2017 and 2023, meeting 2016 World Health Organization criteria for JAK2V617F mutation testing. The JAK2 Somatic Mutation Screening Kit was used for genetic testing. Machine learning models were trained and tested using Python programming language. Out of 458 cases, JAK2V617F mutation was identified in 13.3%. There were significant differences in complete blood count parameters between mutation carriers and non-carriers. Various models were trained with data, with the random forest (RF) model demonstrating superior precision, recall, F1-score, accuracy, and area under the receiver operating characteristic, all reaching 100%. Gradient boosting (GB) model also showed high scores. When compared with existing algorithms, the RF and GB models displayed superior performance. The RF and GB models outperformed other methods in accurately identifying and classifying erythrocytosis cases, offering potential reductions in unnecessary testing and costs.

An Approach to the Investigation of Thrombocytosis: Differentiating between Essential Thrombocythemia and Secondary Thrombocytosis

Background

Thrombocytosis is a common reason for referral to Hematology. Differentiating between secondary causes of thrombocytosis and essential thrombocythemia (ET) is often clinically challenging. A practical diagnostic approach to identify secondary thrombocytosis could reduce overinvestigation such as next generation sequencing (NGS) panel.

Methods and Results

All adult patients with thrombocytosis (≥450 × 109/L) who underwent molecular testing at a single tertiary care centre between January 1, 2018 and May 31, 2021 were evaluated. Clinical and laboratory variables were compared between patients with secondary thrombocytosis vs. ET. Clinical variables included smoking, thrombosis, splenectomy, active malignancy, chronic inflammatory disease, and iron deficiency anemia. Laboratory variables included complete blood count (CBC), ferritin, and myeloid mutations detected by NGS. The overall yield of molecular testing was 52.4%; 92.1% of which were mutations in JAK2, CALR, and/or MPL. Clinical factors predictive of ET included history of arterial thrombosis (p < 0.05); active malignancy, chronic inflammatory disease, splenectomy, and iron deficiency were associated with secondary thrombocytosis (p < 0.05). A diagnosis of ET was associated with higher hemoglobin, mean corpuscular volume (MCV), red cell distribution width (RDW), and mean platelet volume (MPV), while secondary thrombocytosis was associated with higher body mass index, white blood cells, and neutrophils (p < 0.01).

Conclusion

A practical approach to investigating patients with persistent thrombocytosis based on clinical characteristics such as active malignancy, chronic inflammatory disease, splenectomy, and iron deficiency may assist in accurately identifying patients more likely to have secondary causes of thrombocytosis and reduce overinvestigation, particularly costly molecular testing.