Genetic Markers of Erythrocytosis: Can the Presence of JAK2 Mutation Be Determined via Complete Blood Count Parameters and/or Serum Erythropoietin Level?

Introduction: In our study, we aimed to predict the presence of the JAK2V617F mutation using haemogram, biochemical parameters, and serum erythropoietin (EPO) levels in patients with erythrocytosis living at high altitudes.Methods: In this retrospective study, 186 patients who presented with erythrocytosis between 2022 and 2025 and had resided at an altitude of ~1800 metres for at least one year were examined. The presence of erythrocytosis was determined according to the 2022 World Health Organisation criteria. Demographic, haematological, and biochemical parameters, as well as serum EPO levels, of the patients were compared according to the presence of the JAK2V617F mutation. Multivariate logistic regression and ROC analysis were then applied.Results: The study included 186 patients; 151 (81.2%) were negative for the JAK2V617F mutation, and 35 (18.8%) were positive. Mutation-positive patients were significantly older ( p < 0.001). Univariate analyses revealed decreased levels of haemoglobin (p = 0.015), Mean Corpuscular Volume (MCV) (p = 0.029),Mean Corpuscular Hemoglobin (MCH) (p < 0.001), Mean Corpuscular Hemoglobin Concentration (MCHC) (p < 0.001), and EPO (p < 0.001). They significantly increased proliferative parameters, including Red Blood Cell Count (RBC) (p = 0.001), Platelet Count (PLT) (p < 0.001), Red Cell Distribution Width (RDW) (p