Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The subset of CD30-positive anaplastic large cell lymphomas (ALCL) with the NPM-ALK gene fusion arising from the t(2;5)(p23;q35) forms a distinct clinical and prognostic entity. Recently, various cytogenetic, molecular, and protein studies have provided evidence for the existence of several types of variant ALK fusions in up to 20% of ALK+ ALCL, of which only one, a TPM3-ALK fusion resulting from a t(1;2)(q25;p23), has so far been cloned. A cryptic inv(2)(p23q35) has been described as another recurrent cytogenetic alteration involving ALK and an unidentified fusion partner in some ALCL. In a screen for variant ALK gene fusions, we identified two ALCL that were negative for NPM-ALK by reverse transcriptase-polymerase chain reaction, but were positive for cytoplasmic ALK with both polyclonal and monoclonal antibodies to the ALK tyrosine kinase domain, consistent with ALK deregulation by an alteration other than the t(2;5) Case 1 was a T-lineage nodal and cutaneous ALCL in a 52-year-old woman, and Case 2 was a T-lineage nodal ALCL in a 12-year-old girl. FISH analysis confirmed ALK rearrangement in both cases. An inverse polymerase chain reaction approach was then used to identify the ALK translocation partner in Case 1. We found an in-frame fusion of ALK to ATIC, a gene previously mapped to 2q34-q35. We then confirmed by DNA polymerase chain reaction the localization of ATIC to yeast artificial chromosome (YAC) 914E7 previously reported to span the 2q35 break in the inv(2)(p23q35). FISH analysis in Case 1 confirmed rearrangement of YAC 914E7 and fusion to ALK. The ATIC-ALK fusion was confirmed in Case 1 and also identified in Case 2 by conventional reverse transcriptase-polymerase chain reaction using ATIC forward and ALK reverse primers. ATIC encodes an enzyme involved in purine biosynthesis which, like other fusion partners of ALK, is constitutively expressed and appears to contain a dimerization domain. ATIC-ALK fusion resulting from the inv(2)(p23q35) thus provides a third mechanism of ALK activation in ALK+ ALCL.
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PMID:ATIC-ALK: A novel variant ALK gene fusion in anaplastic large cell lymphoma resulting from the recurrent cryptic chromosomal inversion, inv(2)(p23q35). 1070 93

Despite its clinical and histological heterogeneity, anaplastic large cell lymphoma (ALCL) is now a well-recognized clinicopathological entity accounting for 2% of all adult non-Hodgkin's lymphomas (NHL) and about 13% of pediatric NHL. Immunophenotypically, ALCL are of T cell (predominantly) or Null cell type; by definition, cases expressing B cell antigens are officially not included in this entity. The translocation (2;5)(p23;q35) is a recurring abnormality in ALCL; 46% of the ALCL patients bear this signature translocation. This translocation creates a fusion gene composed of nucleophosmin (NPM) and a novel receptor tyrosine kinase gene, named anaplastic lymphoma kinase (ALK). The NPM-ALK chimeric gene encodes a constitutively activated tyrosine kinase that has been shown to be a potent oncogene. The exact pathogenetic mechanisms leading to lymphomagenesis remain elusive; however, the synopsis of evidence obtained to date provides an outline of likely scenarios. Several t(2;5) variants have been described; in some instances, the breakpoints have been cloned and the genes forming a new fusion gene with ALK have been identified: ATIC-ALK, TFG-ALK and TPM3-ALK. Cloning the translocation breakpoint and identifying the ALK and NPM genes provided tools for screening material from patients with ALCL using various approaches at the chromosome, DNA, RNA, or protein level: positive signals in the reverse transcriptase-polymerase chain reaction (RT-PCR) and the immunostaining with anti-ALK monoclonal antibodies (McAb) serve as the most convenient tests for detection of the t(2;5) NPM-ALK since the fusion gene and ALK protein expression do not occur in normal or reactive lymphoid tissue. The wide range of NPM-ALK positivity reported in different series appears to be dependent on the inclusion and selection criteria of the ALCL cases studied. Overall, however, 43% of ALCL cases were NPM-ALK+ (83% of pediatric ALCL vs 31% of adult ALCL). Occasional non-ALCL B cell lymphomas (4%) with diffuse large cell and immunoblastic histology and Hodgkin's disease cases (3%) were NPM-ALK-, but these data are questionable. The aggregate results indicate that, in contrast to primary nodal (systemic) ALCL, the t(2;5) may be present in only 10-20% of primary cutaneous ALCL and rarely, if at all, in lymphomatoid papulosis, a potential precursor lesion; however, these 10-20% positive cases were not confirmed by anti-ALK McAb immunostaining and may represent an overestimate. Positivity for NPM-ALK is associated to various degrees with the following parameters: 44% and 45% of ALCL cases with T cell and Null cell immunophenotype, respectively, are positive, whereas only 8% of cases with a B cell immunoprofile are positive; the mean age of positive patients is significantly younger than that of negative patients; positive cases carry a better overall prognosis (but not in all studies). Recently, the homogenous category of ALK lymphoma ('ALKoma') has emerged as a distinct pathological entity within the heterogenous group of ALCL. The fact that patients with ALK lymphomas experience significantly better overall survival than ALK- ALCL demonstrates further that analysis of ALK expression has important prognostic implications. The term ALK lymphoma signifies a switch in the use of the diagnostic criteria: cases are selected on the basis of a genetic abnormality (the ALK rearrangement), instead of the review of morphological or immunophenotypical features which are clearly more prone to disagreement and controversy. Since its initial description in 1985 ALCL has become one of the best characterized lymphoma entities.
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PMID:Pathobiology of NPM-ALK and variant fusion genes in anaplastic large cell lymphoma and other lymphomas. 1099 99

To evaluate t(2;5) and its variants, we studied 21 pediatric cases of anaplastic lymphoma kinase (ALK)+ anaplastic large cell lymphoma (ALCL) by using immunohistochemical staining, fluorescence in situ hybridization, cytogenetics, and reverse transcriptase-polymerase chain reaction. Results showed 7 (33%) cases with t(2;5), 6 (29%) with variant gene rearrangements, 7 (33%) with uncharacterized rearrangements, and 1 with ALK protein expression but no ALK rearrangement. Among 6 variant gene rearrangements, 1 had TPM4-ALK/t(2;19)(p23;p13) and 2 had inv(2) with the breakpoint proximate to ATIC-ALK and an unknown partner gene separately. The genetic features of the remaining 3 cases were as follows: ins(8;2) with an unknown partner gene; conversion from ALK- at diagnosis to ALK+ at recurrence with unspecified gene rearrangement; complex karyotype without involvement of 2p23, suggesting a cryptic translocation. Concordance between different laboratory results varied from 47% to 81%. These data suggest that ALK variants are not uncommon and underscore the necessity of integrating immunohistochemical, cytogenetic, and molecular genetic approaches to detect, characterize, and confirm t(2;5) and its variant translocations.
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PMID:Assessment of t(2;5)(p23;q35) translocation and variants in pediatric ALK+ anaplastic large cell lymphoma. 1508 Mar 1

We report a 10-year-old girl with ATIC-anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL). She presented with inguinal, axillary, and paraaortic lymph node swellings that showed spontaneous regression over a 3-month period, followed by recurrence after an interval of 8 months. Radiological and clinical findings indicated Ann Arbor stage IIIA. Pathological findings showed that staining of ALK was restricted to the cytoplasm of ALCL cells. ATIC-ALK chimeric transcripts were detected by reverse transcriptase polymerase chain reaction. The patient was assigned to the standard risk group proposed by the international multicenter study for pediatric ALCL, ALCL99. The patient responded well to the treatment and remained in complete remission for more than 26 months. To date, 7 genes have been identified as a fusion partner of ALK, with the highest frequency in nucleophosmin (NPM). Little is known about the clinical implications of subtypes of ALCL harboring each of the 7 fusion genes, especially those of variant fusion genes other than NPM-ALK. In this paper, we review 9 patients with ATIC-ALK-positive ALCL in the literature in addition to discussing our patient. In eight of these 10 cases, disease occurred within the first three decades. Five of 6 cases that were followed continuously remained in complete remission.
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PMID:[ATIC-ALK-positive anaplastic large cell lymphoma: a case report and review of the literature]. 1857 9

In anaplastic large cell lymphoma (ALCL), the anaplastic lymphoma kinase (ALK) gene is rearranged with diverse partners due to variant translocations/inversions. Case 1 was a 39-year-old man who developed multiple tumors in the mediastinum, psoas muscle, lung, and lymph nodes. A biopsy specimen of the inguinal node was effaced by large tumor cells expressing CD30, epithelial membrane antigen, and cytoplasmic ALK, which led to a diagnosis of ALK(+) ALCL. Case 2 was a 51-year-old man who was initially diagnosed with undifferentiated carcinoma. He developed multiple skin tumors eight years after his initial presentation, and was finally diagnosed with ALK(+) ALCL. He died of therapy-related acute myeloid leukemia. G-banding and fluorescence in situ hybridization using an ALK break-apart probe revealed the rearrangement of ALK and suggested variant translocation in both cases. We applied an inverse cDNA polymerase chain reaction (PCR) strategy to identify the partner of ALK. Nucleotide sequencing of the PCR products and a database search revealed that the sequences of ATIC in case 1 and TRAF1 in case 2 appeared to follow those of ALK. We subsequently confirmed ATIC-ALK and TRAF1-ALK fusions by reverse transcriptase PCR and nucleotide sequencing. We successfully determined the partner gene of ALK in two cases of ALK(+) ALCL. ATIC is the second most common partner of variant ALK rearrangements, while the TRAF1-ALK fusion gene was first reported in 2013, and this is the second reported case of ALK(+) ALCL carrying TRAF1-ALK.
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PMID:Variant translocation partners of the anaplastic lymphoma kinase (ALK) gene in two cases of anaplastic large cell lymphoma, identified by inverse cDNA polymerase chain reaction. 2550 Nov 14