Most pediatric patients with essential thrombocythemia show hypersensitivity to erythropoietin in vitro, with rare JAK2 V617F-positive erythroid colonies.
The use of biological markers including JAK2 V617 PCR test, serum EPO, PRV-1, EEC, leukocyte alkaline phosphatase score and peripheral blood parameters combined with bone marrow histopathology has a high sensitivity and specificity (almost 100%) to diagnose the early and overt stages of ET, PV and CIMF in JAK2 V617F positive and negative MPDs.
A comparison of the laboratory features of JAK2 V617-positive and JAK2 wild-type ET patients clearly showed that JAK2 V617-positive ET is characterized by higher values for hemoglobin, hematocrit, and neutrophil counts; lower values for serum erythropoietin (EPO) levels, serum ferritin, and mean corpuscular volume; and by increased cellularity of the bone marrow in biopsy material.
For example, the growth of erythropoietin-independent erythroid colonies, termed "endogenous erythroid colonies (EECs)", has previously been observed in only 50% of ET patients.
Essential thrombocythaemia (ET) is a heterogeneous disorder with respect to plasma erythropoietin concentration at diagnosis and clonality of haematopoiesis.
The presence of a significant association between elevated PRV-1 mRNA expression and low plasma erythropoietin concentration in essential thrombocythaemia.