Myelofibrosis (MF), one of the three classic Philadelphia-chromosome-negative myeloproliferative neoplasms (MPNs), is characterized by symptoms mainly derived from anemia and splenomegaly and constitutional symptoms and associated with a median survival around 6 years. Most MPN patients harbor an acquired mutation in the hemopoietic cells, the V617F mutation, located in the pseudokinase domain of the JAK2 gene. This mutation results in a gain of function, i.e., in the constitutive activation of the JAK-STAT pathway, which plays an important role in the proliferation, differentiation, and survival of the hemopoietic cells, as well as in the immune function. Besides, a minority of patients with MF (most of them negative for the JAK2 mutation) harbor other JAK-STAT-activating mutation, the MPL mutation, in the gene of the receptor of the thrombopoietin. Recently, mutations in the CALR gene have been described in 86% of cases with primary MF that are negative for JAK2 or MPL mutations. CALR mutation also showed cytokine independent growth of cells due to activation of STAT5 involved with the JAK-STAT pathway but its exact role in MPN remains to be clarified.
Category
Cancer
Brite
Human diseases in ICD-11 classification [BR:br08403]
02 Neoplasms
Neoplasms of haematopoietic or lymphoid tissues
Myeloproliferative neoplasms
2A20 Non mast cell myeloproliferative neoplasms
H01605 Myelofibrosis
Pathway-based classification of diseases [BR:br08402]
Signal transduction
nt06518 JAK-STAT signaling
H01605 Myelofibrosis
Cellular process
nt06535 Efferocytosis
H01605 Myelofibrosis
Essential thrombocythemia (ET) is one of the myeloproliferative neoplasms (MPNs), a group of clonal stem cell disorders with similarities at the phenotypic and molecular level. ET is characterized by an isolated thrombocytosis and overlaps clinically with polycythemia vera [DS:H00012] and primary myelofibrosis (PMF) [DS:H01605]. The V617F mutation in the tyrosine pseudokinase region of the JAK2 gene is found in 50 - 60% of ET patients. This mutation produces an increased tyrosine kinase activity of JAK2, resulting in uncontrolled cellular growth in the hematopoietic compartment. Calreticulin (CALR) or myeloproliferative leukemia virus oncogene (MPL) mutations occur in approximately 25%, and 3% of ET patients, respectively.
Category
Hematologic disease
Brite
Human diseases in ICD-11 classification [BR:br08403]
03 Diseases of the blood or blood-forming organs
Coagulation defects, purpura or other haemorrhagic or related conditions
3B63 Thrombocytosis
H01612 Essential thrombocythemia
Pathway-based classification of diseases [BR:br08402]
Signal transduction
nt06518 JAK-STAT signaling
H01612 Essential thrombocythemia
Cellular process
nt06535 Efferocytosis
H01612 Essential thrombocythemia
