Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

High-throughput DNA sequence analysis was used to screen for TET2 mutations in bone marrow-derived DNA from 239 patients with BCR-ABL-negative myeloproliferative neoplasms (MPNs). Thirty-two mutations (19 frameshift, 10 nonsense, 3 missense; mostly involving exons 4 and 12) were identified for an overall mutational frequency of approximately 13%. Specific diagnoses included polycythemia vera (PV; n=89), essential thrombocythemia (ET; n=57), primary myelofibrosis (PMF; n=60), post-PV MF (n=14), post-ET MF (n=7) and blast phase PV/ET/MF (n=12); the corresponding mutational frequencies were approximately 16, 5, 17, 14, 14 and 17% (P=0.50). Mutant TET2 was detected in approximately 17 and approximately 7% of JAK2V617F-positive and -negative cases, respectively (P=0.04). However, this apparent clustering of the two mutations was accounted for by an independent association between mutant TET2 and advanced age; mutational frequency was approximately 23% in patients > or =60 years old versus approximately 4% in younger patients (P<0.0001). The presence of mutant TET2 did not affect survival, leukemic transformation or thrombosis in either PV or PMF; a correlation with hemoglobin <10 g per 100 ml in PMF was noted (P=0.05). We conclude that TET2 mutations occur in both JAK2V617F-positive and -negative MPN, are more prevalent in older patients, display similar frequencies across MPN subcategories and disease stages, and hold limited prognostic relevance.
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PMID:TET2 mutations and their clinical correlates in polycythemia vera, essential thrombocythemia and myelofibrosis. 1926 1

The JAK2(V617F) mutation does not elucidate the phenotypic variability observed in myeloproliferative neoplasm (MPN) families. A putative tumor suppressor gene, TET2, was recently implicated in MPN and myelodysplastic syndromes through the identification of acquired mutations affecting hematopoietic stem cells. The present study analyzed the TET2 gene in 61 MPN cases from 42 families. Fifteen distinct mutations were identified in 12 (20%) JAK2(V617F)-positive or -negative patients. In a patient with 2 TET2 mutations, the analysis of 5 blood samples at different phases of her disease showed the sequential occurrence of JAK2(V617F) and TET2 mutations concomitantly to the disease evolution. Analysis of familial segregation confirmed that TET2 mutations were not inherited but somatically acquired. TET2 mutations were mainly observed (10 of 12) in patients with primary myelofibrosis or patients with polycythemia vera or essential thrombocythemia who secondarily evolved toward myelofibrosis or acute myeloid leukemia.
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PMID:Analysis of the ten-eleven translocation 2 (TET2) gene in familial myeloproliferative neoplasms. 1956 37

The 2008 WHO classification system for hematological malignancies is comprehensive and includes histology and genetic information. Myeloid neoplasms are now classified into five categories: acute myeloid leukemia, myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), MDS/MPN, and myeloid and/or lymphoid malignancies associated with eosinophilia and PDGFR or FGFR1 rearrangements. MPN are subclassified into eight separate entities: chronic myelogenous leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, systemic mastocytosis, chronic eosinophilic leukemia not otherwise specified, chronic neutrophilic leukemia, and unclassifiable MPN. The diagnosis of chronic myelogenous leukemia requires the presence of BCR-ABL1, while its absence is required for all other MPN. Additional MPN-associated molecular markers include mutations of JAK2, MPL, TET2 and KIT. JAK2 V617F is found in most patients with polycythemia vera, essential thrombocythemia, or primary myelofibrosis and is, therefore, useful as a clonal marker in those settings. The diagnostic utility of MPL and TET2 mutations is limited by low mutational frequency. In systemic mastocytosis, presence of KIT D816V is expected but not essential for diagnosis. Chronic eosinophilic leukemia not otherwise specified should be distinguished from both PDGFR-rearranged or FGFR1-rearranged neoplasms and hypereosinophilic syndrome. We discuss histologic, cytogenetic and molecular changes in MPN and illustrate their integration into practical diagnostic algorithms.
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PMID:Myeloproliferative neoplasms: contemporary diagnosis using histology and genetics. 1980 46

In recent years, a series of studies have provided genetic insight into the pathogenesis of myeloproliferative neoplasms (MPNs). It is now known that JAK2V617F mutations are present in 90% of patients with polycythaemia vera (PV), 60% of patients with essential thrombocytosis (ET) and 50% of patients with myelofibrosis (MF). Despite the high prevalence of JAK2V617F mutations in these three myeloid malignancies, several questions remain. For example, how does one mutation contribute to the pathogenesis of three clinically distinct diseases, and how do some patients develop these diseases in the absence of a JAK2V617F mutation? Single nucleotide polymorphisms at various loci and somatic mutations, such as those in MPLW515L/K, TET2 and in exon 12 of JAK2, may also contribute to the pathogenesis of these MPNs. There are likely additional germline and somatic genetic factors important to the MPN phenotype. Additional studies of large MPN and control cohorts with new techniques will help identify these factors.
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PMID:Mechanisms of mutations in myeloproliferative neoplasms. 1995 98

Acute myeloid leukemia (AML) may follow a JAK2-positive myeloproliferative neoplasm (MPN), although the mechanisms of disease evolution, often involving loss of mutant JAK2, remain obscure. We studied 16 patients with JAK2-mutant (7 of 16) or JAK2 wild-type (9 of 16) AML after a JAK2-mutant MPN. Primary myelofibrosis or myelofibrotic transformation preceded all 7 JAK2-mutant but only 1 of 9 JAK2 wild-type AMLs (P = .001), implying that JAK2-mutant AML is preceded by mutation(s) that give rise to a "myelofibrosis" phenotype. Loss of the JAK2 mutation by mitotic recombination, gene conversion, or deletion was excluded in all wild-type AMLs. A search for additional mutations identified alterations of RUNX1, WT1, TP53, CBL, NRAS, and TET2, without significant differences between JAK2-mutant and wild-type leukemias. In 4 patients, mutations in TP53, CBL, or TET2 were present in JAK2 wild-type leukemic blasts but absent from the JAK2-mutant MPN. By contrast in a chronic-phase patient, clones harboring mutations in JAK2 or MPL represented the progeny of a shared TET2-mutant ancestral clone. These results indicate that different pathogenetic mechanisms underlie transformation to JAK2 wild-type and JAK2-mutant AML, show that TET2 mutations may be present in a clone distinct from that harboring a JAK2 mutation, and emphasize the clonal heterogeneity of the MPNs.
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PMID:Two routes to leukemic transformation after a JAK2 mutation-positive myeloproliferative neoplasm. 2037 59

Somatic mutations in TET2 occur in patients with myeloproliferative neoplasms and other hematologic malignancies. It has been suggested that TET2 is a tumor suppressor gene and mutations in TET2 precede the acquisition of JAK2-V617F. To examine the order of events, we performed colony assays and genotyped TET2 and JAK2 in individual colonies. In 4 of 8 myeloproliferative neoplasm patients, we found that some colonies with mutated TET2 carried wild-type JAK2, whereas others were JAK2-V617F positive, indicating that TET2 occurred before JAK2-V617F. One of these patients carried a germline TET2 mutation. However, in 2 other patients, we obtained data compatible with the opposite order of events, with JAK2 exon 12 mutation preceding TET2 mutation in one case. Finally, in 2 of 8 patients, the TET2 and JAK2-V617F mutations defined 2 separate clones. The lack of a strict temporal order of occurrence makes it unlikely that mutations in TET2 represent a predisposing event for acquiring mutations in JAK2.
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PMID:Clonal analysis of TET2 and JAK2 mutations suggests that TET2 can be a late event in the progression of myeloproliferative neoplasms. 2131 Sep 37

The oncogenetic events that transform chronic myeloproliferative neoplasms (MPN) to acute myeloid leukemias (AML) are not well characterized. We investigated the role of several genes implicated in leukemic transformation by mutational analysis of 63 patients with AML secondary to a preexisting MPN (sAML). Frequent mutations were identified in TET2 (26.3%), ASXL1 (19.3%), IDH1 (9.5%), and JAK2 (36.8%) mutations in sAML, and all possible mutational combinations of these genes were also observed. Analysis of 14 patients for which paired samples from MPN and sAML were available showed that TET2 mutations were frequently acquired at leukemic transformation [6 of 14 (43%)]. In contrast, ASXL1 mutations were almost always detected in both the MPN and AML clones from individual patients. One case was also observed where TET2 and ASXL1 mutations were found before the patient acquired a JAK2 mutation or developed clinical evidence of MPN. We conclude that mutations in TET2, ASXL1, and IDH1 are common in sAML derived from a preexisting MPN. Although TET2/ASXL1 mutations may precede acquisition of JAK2 mutations by the MPN clone, mutations in TET2, but not ASXL1, are commonly acquired at the time of leukemic transformation. Our findings argue that the mutational order of events in MPN and sAML varies in different patients, and that TET2 and ASXL1 mutations have distinct roles in MPN pathogenesis and leukemic transformation. Given the presence of sAML that have no preexisting JAK2/TET2/ASXL1/IDH1 mutations, our work indicates the existence of other mutations yet to be identified that are necessary for leukemic transformation.
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PMID:Genetic analysis of transforming events that convert chronic myeloproliferative neoplasms to leukemias. 2006 84

Myelodysplastic syndromes and acute myeloid leukemia with an isodicentric X chromosome [idic(X)(q13)] occur in elderly women and frequently display ringed sideroblasts. Because of the rarity of idic(X)(q13), little is known about its formation, whether a fusion gene is generated, and patterns of additional aberrations. We here present an SNP array study of 14 idic(X)-positive myeloid malignancies, collected through an international collaborative effort. The breakpoints clustered in two regions of segmental duplications and were not in a gene, making dosage effects from the concurrent gain of Xpter-q13 and loss of Xq13-qter, rather than a fusion gene, the most likely pathogenetic outcome. Methylation analysis revealed involvement of the inactive X chromosomes in five cases and of the active in two. The ABCB7 gene, mutated in X-linked sideroblastic anemia and spinocerebellar ataxia, is in the deleted region, suggesting that loss of this gene underlies the frequent presence of ringed sideroblasts. Additional genetic abnormalities were present in 12/14 (86%), including partial uniparental disomies for 9p (one case) and 4q (two cases) associated with homozygous mutations of JAK2 and TET2, respectively. In total, TET2 mutations were seen in 4/11 (36%) analyzed cases, thus constituting a common secondary event in idic(X)-positive malignancies.
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PMID:The idic(X)(q13) in myeloid malignancies: breakpoint clustering in segmental duplications and association with TET2 mutations. 2009 95

Single nucleotide polymorphism arrays (SNP-A) have recently been widely applied as a powerful karyotyping tool in numerous translational cancer studies. SNP-A complements traditional metaphase cytogenetics with the unique ability to delineate a previously hidden chromosomal defect, copy neutral loss of heterozygosity (CN-LOH). Emerging data demonstrate that selected hematologic malignancies exhibit abundant CN-LOH, often in the setting of a normal metaphase karyotype and no previously identified clonal marker. In this review, we explore emerging biologic and clinical features of CN-LOH relevant to hematologic malignancies. In myeloid malignancies, CN-LOH has been associated with the duplication of oncogenic mutations with concomitant loss of the normal allele. Examples include JAK2, MPL, c-KIT, and FLT3. More recent investigations have focused on evaluation of candidate genes contained in common CN-LOH and deletion regions and have led to the discovery of tumor suppressor genes, including c-CBL and family members, as well as TET2. Investigations into the underlying mechanisms generating CN-LOH have great promise for elucidating general cancer mechanisms. We anticipate that further detailed characterization of CN-LOH lesions will probably facilitate our discovery of a more complete set of pathogenic molecular lesions, disease and prognosis markers, and better understanding of the initiation and progression of hematologic malignancies.
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PMID:Copy neutral loss of heterozygosity: a novel chromosomal lesion in myeloid malignancies. 2010 30

The pathogenesis of myelodysplastic syndromes involves a pattern of genetic, epigenetic, and immune-mediated mechanisms but little is known about what causes the specific disease features and promotes disease progression in the individual patient. The identification of JAK2 and MPL mutations, and more recently TET2, CBL and ASXL-1 mutations in these disorders provide a basis for increased understanding of disease biology and mechanisms behind progression. Such mutations are more commonly found in patients with a significant amount of marrow ring sideroblasts, and in patients belonging to the category of mixed myelodysplastic/myeloproliferative neoplasms, entities which are in focus for this review.
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PMID:Significance of JAK2 and TET2 mutations in myelodysplastic syndromes. 2017 68


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