Absence of JAK2V617F mutation in patients with beta-thalassemia major and thrombocytosis due to splenectomy

Polycythemia Vera in a Patient With Heterozygous Beta-Thalassemia: Coincidence or Causal Relationship?

Polycythemia vera (PV) and heterozygous beta-thalassemia (HBT) have opposing effects on the hematocrit (Hct) and may mask the presence of each other. Missing the diagnosis of PV may have serious consequences, mainly by exposing the patient to the risk of thromboses. We present a case where the diagnosis of PV was delayed due to the coexistence of HBT, and review the relevant literature. It can be postulated that "stress erythropoiesis", known to occur in patients with thalassemic syndromes, increases the probability of somatic JAK2 mutations leading to development of PV.

Investigation of JAK2V617F Mutation Prevalence in Patients with Beta Thalassemia Major

BACKGROUND

Beta (β)-thalassemia major is a genetic disorder with anemia and an increased level of erythropoietin by Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway. JAK plays an important role in cell signaling, and the common mutation in the JAK2 gene in myeloid disorders is called JAK2V617F.

METHODS

A total of 75 patients with beta (β)-thalassemia major patients, including 34 males (45%) and 41 females (55%), were enrolled in this study. The presence of the JAK2V617F mutation was assessed using the amplification-refractory mutation-polymerase chain reaction (ARMS-PCR) technique.

RESULTS

Among the 75 patients, 14 patients (19%) tested positive and 61 patients (81%) tested negative for JAK2V617F mutation. We observed no statistically significant difference in sex, age, genotype, and JAK2V617F mutation among patients (P> .05). However, a significant difference between blood-transfusion frequency and JAK2V617F mutation was observed (P <.05).

CONCLUSION

Due to the low prevalence of JAK2V617F mutation in thalassemia, using a larger population of the patients to investigate this mutation in ineffective erythropoiesis can be useful.

Co-existence of myeloproliferative neoplasias and β-thalassemia with IVS-2-654 mutation-a case report

Thalassemia and myeloproliferative neoplasias (MPNs) are recognized as two separate diseases. Thalassemia is a hemolytic disease caused by abnormal goblin genes, which results in the deficiency of globin chains. MPNs are clonal hematopoietic stem cell diseases characterized by the proliferation of multiple myeloid lineages. The coexistence of thalassemia and myeloproliferative neoplasia are rarely reported. We herein describe a case of a 24-year-old woman, previously diagnosed as β-thalassemia, with a lifelong history of thrombocytosis. She was subsequently diagnosed as low-risk essential thrombocythemia (ET), one of the MPNs. The patient was treated with folic acid supplementation and Iron-chelating therapy, without aspirin or cytoreductive therapy. Up to date, no thrombotic events or disease-related bleeding are happening to the patient, who remains in good health. Furthermore, we found three novel genes mutations EP300, CUX1, and FGFR3 after next-generation sequencing. We presume that the mutations of these genes in β-thalassemia might have an impact on the happening of ET and therefore need further investigations.

Acute Non-Atherosclerotic ST-Segment Elevation Myocardial Infarction in an Adolescent with Concurrent Hemoglobin H-Constant Spring Disease and Polycythemia Vera

Thrombosis is a major complication of polycythemia vera (PV) and also a well-known complication of thalassemia. We reported a case of non-atherosclerotic ST-segment elevation myocardial infarction (STEMI) in a 17-year-old man with concurrent post-splenectomized hemoglobin H-Constant Spring disease and JAK2 V617F mutation-positive PV. The patient initially presented with extreme thrombocytosis (platelet counts greater than 1,000,000/µL) and three months later developed an acute STEMI. Coronary artery angiography revealed an acute clot in the right coronary artery without atherosclerotic plaque. He was treated with plateletpheresis, hydroxyurea and antiplatelet agents. The platelet count decreased and his symptoms improved. This case represents the importance of early diagnosis, awareness of the increased risk for thrombotic complications, and early treatment of PV in patients who have underlying thalassemia with marked thrombocytosis.

Polycythemia vera and the Jak2(V617F) mutation in a case of hereditary spherocytosis

The identification of Jak2(V617F) mutations in more than 90% of patients with polycythemia vera (PV) has greatly improved the diagnostic accuracy for this uncommon myeloproliferative disorder. Although previous cases of presumptive PV in patients with hereditary spherocytosis (HS) have been described, these earlier reports either preceded the establishment of widely accepted criteria for the diagnosis of PV or lacked definitive studies to rule out secondary causes of polycythemia. In contrast, the author describes here a novel case of PV confirmed at the molecular level in a patient with hereditary spherocytosis by the finding of a Jak2(V617F) mutation. Based on recent advances in understanding the role of Jak2 signaling in the pathogenesis of PV, the author proposes 2 independent biological mechanisms that could account for more than a chance association of these 2 disorders.