TRG

Gene Summary

Gene:TRG; T cell receptor gamma locus
Aliases: TCRG, TRG@
Location:7p14
Summary:T cell receptors recognize foreign antigens which have been processed as small peptides and bound to major histocompatibility complex (MHC) molecules at the surface of antigen presenting cells (APC). Each T cell receptor is a dimer consisting of one alpha and one beta chain or one delta and one gamma chain. In a single cell, the T cell receptor loci are rearranged and expressed in the order delta, gamma, beta, and alpha. If both delta and gamma rearrangements produce functional chains, the cell expresses delta and gamma. If not, the cell proceeds to rearrange the beta and alpha loci. This region represents the germline organization of the T cell receptor gamma locus. The gamma locus includes V (variable), J (joining), and C (constant) segments. During T cell development, the gamma chain is synthesized by a recombination event at the DNA level joining a V segment with a J segment; the C segment is later joined by splicing at the RNA level. Recombination of many different V segments with several J segments provides a wide range of antigen recognition. Additional diversity is attained by junctional diversity, resulting from the random addition of nucleotides by terminal deoxynucleotidyltransferase. Several V segments of the gamma locus are known to be incapable of encoding a protein and are considered pseudogenes. Somatic rearrangement of the gamma locus has been observed in T cells derived from patients with T cell leukemia and ataxia telangiectasia. [provided by RefSeq, Jul 2008]
Databases:HGNC, GeneCard, Gene
Source:NCBIAccessed: 27 February, 2015

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 28 February 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • T-Cell Lymphoma
  • Vascular Neoplasms
  • Melanoma
  • Gene Rearrangement
  • Cutaneous T-cell lymphoma
  • Immunoglobulin Heavy Chains
  • B-Lymphocytes
  • Immunophenotyping
  • Cancer DNA
  • DNA Primers
  • Immunohistochemistry
  • Skin Cancer
  • Tumor Markers
  • DNA Sequence Analysis
  • Thyroiditis, Autoimmune
  • Childhood Cancer
  • Polymerase Chain Reaction
  • Adolescents
  • Chromosome 7
  • Base Sequence
  • Mycosis Fungoides
  • Southern Blotting
  • Molecular Sequence Data
  • Genetic Recombination
  • Genes, Immunoglobulin
  • Paraffin Embedding
  • Biopsy
  • Acute Lymphocytic Leukaemia
  • Translocation
  • Infant
  • Recurrence
  • TRG
  • T-Lymphocyte Gene Rearrangement
  • Immunoglobulins
  • Adult T-Cell Leukemia-Lymphoma
  • Breast Cancer
  • Clone Cells
  • T-Cell Antigen Receptors
  • Receptors, Antigen, T-Cell, gamma-delta
  • Gamma-Chain T-Cell Antigen Receptor Gene Rearrangement
  • Residual Disease
  • Reproducibility of Results
Tag cloud generated 27 February, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: TRG (cancer-related)

Ai X, Fu Q, Wang J, et al.
[Significance of BIOMED-2 standardized IG/TCR gene rearrangement detection in paraffin-embedded section in lymphoma diagnosis].
Zhonghua Xue Ye Xue Za Zhi. 2014; 35(6):495-8 [PubMed] Related Publications
OBJECTIVE: To explore the feasibility of detecting lymphoma with the application of BIOMED-2 standardized immunoglobulin/T cell receptor (IG/TCR) gene rearrangement system in formalin fixed paraffin-embedded (FFPE) tissue samples, and to discuss the relationship between the longest amplification fragment of extracted DNA and positive detection rate of different IGH V-J primers.
METHODS: DNA was extracted from 50 cases of FFPE tissue samples. Multiplex-PCR amplifications were performed and then the IG/TCR gene rearrangements were analyzed using BIOMED-2 standardized clonality analysis system.
RESULTS: (1)When the DNA concentration was diluted to 50-100 ng/μl from 100-500 ng/μl, the proportion of the longest amplification fragment (300-400 bp) of DNA was improved from 10.0% to 90.0% in 30 cases of diffuse large B cell lymphoma (DLBCL) wax roll samples (P<0.01). The positive rate of IGH+IGK was increased from 46.7% to 83.3%, the difference was statistically significant (P=0.006). The lengths of the longest amplification fragments of DNA were all longer than 300 bp in the paraffin section samples of DLBCL. The positive rate of IGH+IGK of these samples was 96.7%. The difference of the positive rate of IGH+IGK between the wax roll samples and the paraffin section samples had no statistical significance (P=0.195). (2)When the concentration of DNA was high, most of the longest amplification fragments of extracted DNA were 100 bp or 200 bp, and the detection rate of short fragment IGH FR3 was more stable than that of long fragment IGH FR1. (3)The clonality analysis of TCRG+TCRB in all 13 cases of peripheral T cell lymphoma samples showed positive results, while no positive IG/TCR clones were found in 7 cases of reactive lymphoid tissue hyperplasia in control group.
CONCLUSION: Dilution of DNA is the only method to improve not only the proportion of longest fragment amplification but also the detection rate of clonality. The detection rate of IGH FR3 would not be affected by the concentration of DNA. The application of BIOMED-2 standardized IG/TCR gene rearrangement system in FFPE tissue samples plays an important role in the lymphoma diagnosis.

Sugimoto KJ, Shimada A, Wakabayashi M, et al.
T-cell lymphoblastic leukemia/lymphoma with t(7;14)(p15;q32) [TCRγ-TCL1A translocation]: a case report and a review of the literature.
Int J Clin Exp Pathol. 2014; 7(5):2615-23 [PubMed] Free Access to Full Article Related Publications
A 22-year-old man sought medical advice for a swelling in the right side of the neck in December 2011. Histopathological examination of the lymph node biopsy initially suggested reactive lymphadenitis, on account of the only sparse presence of tumor cells. Bone marrow examination was performed in February 2012 revealed findings consistent with a diagnosis of T-cell lymphoblastic leukemia/lymphoma (T-LBL), and the patient was begun on remission induction therapy. The bone marrow showed an immature thymocytic pattern: cytoplasmic CD3+, surface CD3-, CD5+, CD4-, and CD8-. Re-assessment of the lymph node specimens revealed the same phenotype of the cells in the lymph node as that of the blasts in the bone marrow. In addition, a chromosomal aberration t(7;14)(p15;q32) was noted. The lymph node biopsy specimens were examined by paraffin-embedded tissue section-fluorescence in situ hybridization (PS-FISH), which revealed a fusion signal of T-cell receptor (TCR)γ gene (7p15) with T-cell leukemia/lymphoma 1A (TCL1A) gene (14q32.13). There have been at least 10 reported cases of T-LBL with t(7;14)(p15;q32), including the present case. However, this is the first reported case in which TCRγ-TCL1A translocation was confirmed by FISH.

Mok MM, Du L, Wang CQ, et al.
RUNX1 point mutations potentially identify a subset of early immature T-cell acute lymphoblastic leukaemia that may originate from differentiated T-cells.
Gene. 2014; 545(1):111-6 [PubMed] Related Publications
The RUNX1/AML1 gene is among the most frequently mutated genes in human leukaemia. However, its association with T-cell acute lymphoblastic leukaemia (T-ALL) remains poorly understood. In order to examine RUNX1 point mutations in T-ALL, we conducted an amplicon-based deep sequencing in 65 Southeast Asian childhood patients and 20 T-ALL cell lines, and detected RUNX1 mutations in 6 patients (9.2%) and 5 cell lines (25%). Interestingly, RUNX1-mutated T-ALL cases seem to constitute a subset of early immature T-ALL that may originate from differentiated T-cells. This result provides a deeper insight into the mechanistic basis for leukaemogenesis.

Poopak B, Saki N, Purfatholah AA, et al.
Pattern of immunoglobulin and T-cell receptor-δ/γ gene rearrangements in Iranian children with B-precursor acute lymphoblastic leukemia.
Hematology. 2014; 19(5):259-66 [PubMed] Related Publications
INTRODUCTION: Acute lymphoblastic leukemia (ALL) cells have unique rearranged immunoglobulin heavy chain (IgH), immunoglobulin light chain (IgK), and T-cell receptor (TCR) genes, which can be used as markers for clonality assay and evaluation of minimal residual disease. In this study, we have evaluated the pattern of IgH, IgK chains, and TCRG/D gene rearrangements in precursor-B ALL.
MATERIALS AND METHODS: In our prospective study, hyper-variable regions (CDRI and III) of IgH, TCRD (Vδ2-Dδ3 and Dδ2-Dδ3), TCRG (Vγ, VγI, and VγII), and IgK (Vκ-Kde) were studied in 126 cases with diagnosis of B-precursor ALL.
RESULTS: One hundred and fourteen (90.5%) out of 126 patients had clonal rearrangements of IgH using consensus primers for CDRI and/or CDRIII regions. Monoclonal, biclonal, and oligoclonal patterns were observed in 63 (57.8%), 38 (34.9%), and 6 (5.5%) patients with IgH (CDRIII) rearrangements, respectively. Clonal rearrangements of TCRG (Vγ) and VγI/II were present in 79.3 and 64.9% of patients, respectively, and only 5% of cases showed biclonal pattern. The VγII rearrangement was the most common (46.8%) type in TCRG. Vδ2-Dδ3 and Dδ2-Dδ3 partial gene rearrangements were observed in 47 (45.2%; n = 104) and 11 (16.6%; n = 66) patients, respectively. Biclonal/oligoclonal patterns were present in 13 (27.7%) and 2 (4.3%) cases with Vδ2-Dδ3 rearrangement, respectively. Only one patient had biclonal Dδ2-Dδ3 rearrangement. Clonal pattern of IgK-Kde was detected in 59 cases (67%; n = 88).
CONCLUSION: Our findings showed that clonal rearrangements of IgH and TCRD (Vδ2-Dδ3 and Dδ2-Dδ3) genes had similar patterns to other studies. Frequency of TCRG (VγI and VγII) and IgK rearrangements was found to be slightly higher than previous reports. Among the IgK rearrangements, VKI (25%) was the most common.

Wang E, Papavassiliou P, Wang AR, et al.
Composite lymphoid neoplasm of B-cell and T-cell origins: a pathologic study of 14 cases.
Hum Pathol. 2014; 45(4):768-84 [PubMed] Related Publications
We retrospectively analyzed 14 composite lymphoma/lymphoid neoplasms (CL) of B-cell/T-cell origins. These consisted of a spectrum of T-cell neoplasms in combination with different B-cell lymphomas/leukemias, with peripheral T-cell lymphoma and diffuse large B-cell lymphoma encountered most frequently for each respective neoplastic lineage. Histopathologic evaluation demonstrated 6 patterns of neoplastic distribution, including zone, inverted zone, diffuse mixed, regional/nodular mixed, compartmental, and segmental distributions. Four of 9 cases studied were positive for Epstein-Barr virus, all with a mixed pattern, suggesting that this pattern may predict an Epstein-Barr virus association. None of 14 cases was considered CL at the initial histologic evaluation. Only 6 (46.2%) of 13 cases had coexisting B-cell/T-cell neoplasms highlighted by immunohistochemistry, and the other 7 (53.8%) cases had 1 or both of the neoplastic components hidden. Flow cytometry detected both neoplastic lineages in 4 (44%) but failed to detect a clonal B-cell population in 4 (44%) and missed neoplastic T cells in 1 (11.1%) of 9 cases. Molecular testing detected clonal rearrangement of IGH/K gene in 11 (84.6%) of 13 cases, and clonal rearrangement of the TCRG/B gene in 13 (92.9%) of 14 cases, including 8 with identical amplicons detected in separate samples. CLs of B-cell/T-cell origin are heterogeneous in subtype combination and topographic pattern, often with one of the components histologically occult. A multidisciplinary approach is emphasized to establish a definitive diagnosis in these challenging cases.

Schumacher JA, Duncavage EJ, Mosbruger TL, et al.
A comparison of deep sequencing of TCRG rearrangements vs traditional capillary electrophoresis for assessment of clonality in T-Cell lymphoproliferative disorders.
Am J Clin Pathol. 2014; 141(3):348-59 [PubMed] Related Publications
OBJECTIVES: To design and evaluate a next-generation sequencing (NGS)-based method for T-cell receptor γ (TCRG) gene-based T-cell clonality testing on the Ion Torrent Personal Genome Machine (Life Technologies, Carlsbad, CA) platform.
METHODS: We analyzed a series of peripheral blood, bone marrow, and formalin-fixed paraffin-embedded tissue specimens with NGS vs traditional capillary electrophoresis methods.
RESULTS: Using a custom analysis algorithm that we developed, our NGS assay identified between 2,215 and 48,222 unique TCRG rearrangements in a series of 48 samples. We established criteria for assigning clonality based on parameters derived from both the relative and absolute frequencies of reads. In a comparison with standard capillary electrophoresis, 19 of 19 polyclonal samples and 24 of 27 samples that appeared clonal were in agreement. The three discrepant samples demonstrated some of the pitfalls of amplicon length-based testing. Dilution studies with T-lymphoid cell lines demonstrated that a known clonal sequence could be routinely identified when present in as few as 0.1% of total cells demonstrating suitability in residual disease testing. A series of samples was also analyzed on a second NGS platform and yielded very similar results with respect to the frequency and sequence of the clonal rearrangement.
CONCLUSIONS: In this proof-of-concept study, we describe an NGS-based T-cell clonality assay that is suitable for routine clinical testing either alone or as an adjunct to traditional methods.

Hsi AC, Kreisel FH, Frater JL, Nguyen TT
Clinicopathologic features of adult T-cell leukemias/lymphomas at a North American tertiary care medical center: infrequent involvement of the central nervous system.
Am J Surg Pathol. 2014; 38(2):245-56 [PubMed] Related Publications
Human T-cell lymphotropic virus type 1 is associated with adult T-cell leukemia/lymphoma (ATLL). Published series of ATLLs seen at a United States medical institution are rare. We present the features of 4 ATLLs diagnosed at our North American tertiary care medical center from 1990 to 2012. Despite the absence of a history of origin from an endemic region, all our ATLLs demonstrated evidence of human T-cell lymphotropic virus type 1 infection. Central nervous system (CNS) involvement by ATLL was uncommon in our series, and represented only 1.6% (1/64) of all CNS B-cell or T-cell lymphomas diagnosed over a 20+ year period at our institution. Review of the medical literature reveals that the majority of CNS-involved ATLLs present with the lymphoma or acute subtype, and complete remission is difficult to achieve in these cases. CNS involvement frequently occurs with a systemic disease, which carries an aggressive clinical course with poor prognosis. In addition, CNS involvement by ATLL can be the initial presentation or seen with relapsed disease, can be the only site or be associated with other tissue sites of involvement, and may manifest with variable clinical signs/symptoms. Our retrospective study reveals that ATLLs are rare mature T-cell lymphomas in a native North American population, but the clinical and histopathologic features of ATLLs from this nonendemic region are similar to those seen from other endemic regions. Early recognition of these rare ATLLs involving uncommon sites, such as the CNS, will help optimize treatment for these infrequent mature T-cell lymphomas.

Vigliar E, Cozzolino I, Picardi M, et al.
Lymph node fine needle cytology in the staging and follow-up of cutaneous lymphomas.
BMC Cancer. 2014; 14:8 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Lymph nodal involvement is an important clinical-pathological sign in primary cutaneous lymphoma (PCL), as it marks the transformation/evolution of the disease from localized to systemic; therefore the surveillance of lymph nodes is important in the staging and follow up of PCL. Fine needle cytology (FNC) is widely used in the diagnosis of lymphadenopathies but has rarely been reported in PCL staging and follow-up. In this study an experience on reactive and neoplastic lymphadenopathies arisen in PCL and investigated by FNC, combined to ancillary techniques, is reported.
METHODS: Twenty-one lymph node FNC from as many PCL patients were retrieved; 17 patients had mycosis fungoides (MF) and 4 a primary cutaneous B-cell lymphoma (PBL). In all cases, rapid on site evaluation (ROSE) was performed and additional passes were used to perform flow cytometry (FC), immunocytochemistry (ICC) and/or polymerase chain reaction (PCR) to assess or rule out a possible clonality of the corresponding cell populations.
RESULTS: FNC combined with FC, ICC, and PCR identified 12 cases of reactive, non specific, hyperplasia (BRH), 4 dermatopathic lymphadenopathy (DL), 4 lymph nodal involvement by MF and 1 lymph nodal involvement by cutaneous B-cell lymphoma.
CONCLUSIONS: FNC coupled with ancillary techniques is an effective tool to evaluate lymph node status in PCL patients, provided that ROSE and a rational usage of ancillary techniques is performed according to the clinical context and the available material. The method can be reasonably used as first line procedure in PCL staging and follow up, avoiding expensive and often ill tolerated biopsies when not strictly needed.

Yasuda K, Matsuki Y, Kobari S, et al.
TCRγ rearrangement and Epstein- Barr virus are detected both in lymphadenopathy of adult-onset Still's disease and in accompanying peripheral T-cell lymphoma.
Pathol Int. 2013; 63(11):568-72 [PubMed] Related Publications

Shan GD, Hu FL, Yang M, et al.
Clonal immunoglobulin heavy chain and T-cell receptor γ gene rearrangements in primary gastric lymphoma.
World J Gastroenterol. 2013; 19(34):5727-31 [PubMed] Free Access to Full Article Related Publications
AIM: To study the diagnostic value of immunoglobulin heavy chain (IgH) and T-cell receptor γ (TCR-γ) gene monoclonal rearrangements in primary gastric lymphoma (PGL).
METHODS: A total of 48 patients with suspected PGL at our hospital were prospectively enrolled in this study from January 2009 to December 2011. The patients were divided into three groups (a PGL group, a gastric linitis plastica group, and a benign gastric ulcer group) based on the pathological results (gastric mucosal specimens obtained by endoscopy or surgery) and follow-up. Endoscopic ultrasonography (EUS) and EUS-guided biopsy were performed in all the patients. The tissue specimens were used for histopathological examination and for IgH and TCR-γ gene rearrangement polymerase chain reaction analyses.
RESULTS: EUS and EUS-guided biopsy were successfully performed in all 48 patients. In the PGL group (n = 21), monoclonal IgH gene rearrangements were detected in 14 (66.7%) patients. A positive result for each set of primers was found in 12 (57.1%), 8 (38.1%), and 4 (19.0%) cases using FR1/JH, FR2/JH, and FR3/JH primers, respectively. Overall, 12 (75%) patients with mucosal-associated lymphoid tissue lymphoma (n = 16) and 2 (40%) patients with diffuse large B-cell lymphoma (n = 5) were positive for monoclonal IgH gene rearrangements. No patients in the gastric linitis plastica group (n = 17) and only one (10%) patient in the benign gastric ulcer group (n = 10) were positive for a monoclonal IgH gene rearrangement. No TCR-γ gene monoclonal rearrangements were detected. The sensitivity of monoclonal IgH gene rearrangements was 66.7% for a PGL diagnosis, and the specificity was 96.4%. In the PGL group, 8 (100%) patients with stage IIE PGL (n = 8) and 6 (46.1%) patients with stage IE PGL (n = 13) were positive for monoclonal IgH gene rearrangements.
CONCLUSION: IgH gene rearrangements may be associated with PGL staging and may be useful for the diagnosis of PGL and for differentiating between PGL and gastric linitis plastica.

Hartmann S, Helling A, Döring C, et al.
Clonality testing of malignant lymphomas with the BIOMED-2 primers in a large cohort of 1969 primary and consultant biopsies.
Pathol Res Pract. 2013; 209(8):495-502 [PubMed] Related Publications
The introduction of the BIOMED-2 primers allowed for reliable comparisons of clonality testing data of malignant lymphomas from different laboratories. This study undertook a retrospective analysis of a large cohort of cases; 1862 cases involved the immunoglobulin heavy chain locus (IGH VH-JH), and 1527 cases involved the T cell receptor gamma locus (TCRG). We confirmed previously published clonality rates in various B cell, T cell, and Hodgkin lymphoma cases. In reactive lesions, clonality for the IGH locus was frequently accompanied by additional polyclonal background. Clonality for TCRG was found in a subgroup of diffuse large B cell lymphomas. On closer morphologic inspection, seven cases appeared to have arisen from an underlying peripheral T-cell lymphoma. Five cases with monoclonal TCRG rearrangements, originally diagnosed as Hodgkin lymphomas, were reclassified as T-cell lymphomas. TCRG clonality was very rarely only observed in Hodgkin lymphoma. In case of clear TCRG clonality a T-cell neoplasia must be ruled out on morphological grounds. By careful examination of the rearrangement patterns, including an assessment of a co-amplified polyclonal background, clonality testing provides a powerful tool which in concert with morphologic and immunohistochemical parameters can lead to a firm diagnosis.

Van Vlierberghe P, Ambesi-Impiombato A, De Keersmaecker K, et al.
Prognostic relevance of integrated genetic profiling in adult T-cell acute lymphoblastic leukemia.
Blood. 2013; 122(1):74-82 [PubMed] Free Access to Full Article Related Publications
Adult T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic tumor associated with poor outcome. In this study, we analyzed the prognostic relevance of genetic alterations, immunophenotypic markers, and microarray gene expression signatures in a panel of 53 adult T-ALL patients treated in the Eastern Cooperative Oncology Group E2993 clinical trial. An early immature gene expression signature, the absence of bi-allelic TCRG deletion, CD13 surface expression, heterozygous deletions of the short arm of chromosome 17, and mutations in IDH1/IDH2 and DNMT3A genes are associated with poor prognosis in this series. In contrast, expression of CD8 or CD62L, homozygous deletion of CDKN2A/CDKN2B, NOTCH1 and/or FBXW7 mutations, and mutations or deletions in the BCL11B tumor suppressor gene were associated with improved overall survival. Importantly, the prognostic relevance of CD13 expression and homozygous CDKN2A/CDKN2B deletions was restricted to cortical and mature T-ALLs. Conversely, mutations in IDH1/IDH2 and DNMT3A were specifically associated with poor outcome in early immature adult T-ALLs. This trial was registered at www.clinicaltrials.gov as #NCT00002514.

Gao LM, Liu WP, Yang QP, et al.
Aggressive natural killer-cell leukemia with jaundice and spontaneous splenic rupture: a case report and review of the literature.
Diagn Pathol. 2013; 8:43 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: Aggressive natural killer cell leukemia/lymphoma (ANKL) is a rare aggressive form of NK-cell neoplasm. We report an uncommon case of 36-year-old male who showed jaundice and spontaneous splenic rupture. The diagnosis was established by the biopsy of liver and spleen. The monomorphous medium-size neoplastic cells infiltrated into portal areas and sinus of liver as well as the cords and sinus of the spleen. Necrosis, mitotic figures and significant apoptosis could be seen easily. These neoplastic cells demonstrated a typical immunophenotype of CD3ε+, CD56+, CD16+, Granzyme B+, TIA-1+. T-cell receptor γ (TCR-γ) gene rearrangement analysis showed germline configuration and the result of in situ hybridization for Epstein-Barr virus-encoded RNA (EBER-ISH) was positive. The patient has undergone an aggressive clinical course and died of multi-organ function failure 14 days later after admission. To the best of our knowledge, this is the first case of ANKL with spontaneous splenic rupture, and we should pay more attention to recognize it.
VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2048154883890867.

Whitling NA, Shanesmith RP, Jacob L, et al.
Composite lymphoma of mycosis fungoides and cutaneous small B-cell lymphoma in a 73-year-old male patient.
Hum Pathol. 2013; 44(4):670-5 [PubMed] Related Publications
Composite lymphoma of T-cell and B-cell type is uncommon, and the one occurring primarily on skin is extremely rare. Herein, we report a unique case of composite lymphoma of mycosis fungoides and cutaneous small B-cell lymphoma in a 73-year-old male patient. The patient presented with multiple erythematous patches, plaques, and nodules on the upper arms, scalp, and trunk. Four punch biopsies of arm and scalp lesions demonstrated lymphoid infiltrate in superficial to deep dermis with a characteristic zone distribution of T-cell and B-cell components. T cells were distributed in papillary and perifollicular dermis and displayed a larger size with convoluted nuclei, whereas B cells were small sized, assuming nodular infiltrate in mid-deep dermis with coexpression of CD5. Molecular test detected clonal rearrangement of both TCRG and IGH/K genes with identical amplicons for each gene in all 4 biopsies. Clinical staging revealed no extracutaneous lesions. A multidisplinary approach is emphasized to establish a definitive diagnosis.

Matsushita Y, Takeshita M
Paediatric T-cell lymphoma of the appendix: a case report.
Diagn Pathol. 2013; 8:2 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: A 7-year-old boy with no history of malnutrition or diarrhoea complained of acute abdominal pain, was diagnosed with acute appendicitis, and underwent appendectomy. Histologically, a diffuse infiltrate of large atypical lymphoid cells was found in the entire appendiceal wall. Immunohistochemical examination revealed that the tumour cells expressed T-cell receptor (TCR)-βF1, CD3, CD4, CD25, cytotoxic-related protein TIA1 and granzyme-B, but were negative for CD8, Foxp3, CD20, CD30 and CD56. Polymerase chain reaction (PCR) revealed clonal bands of TCR-γ gene products in the tumour tissue. No anti-cytomegalovirus antibody-positive cells were detected. In situ hybridization revealed no nuclear signals of Epstein-Barr virus (EBV)-encoded RNA. Helicobacter pylori infection was detected in tumour tissue by anti-East Asian cytotoxin-associated gene (Cag) A antibody and PCR using its specific primers. The patient received chemotherapy and has remained in remission for 2 years. To the best of our knowledge, only two cases of appendiceal T-cell non-Hodgkin lymphoma (NHL) have been reported, both in elderly patients. We believe that this is the first reported case of childhood CD4- and TIA1-positive cytotoxic T (Th1)-cell NHL in the appendix or gastrointestinal tract. Helicobacter pylori infection might be an initiator of atypical cytotoxic T-cell proliferation.
VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1302380563830412.

Boone E, Verhaaf B, Langerak AW
PCR-based analysis of rearranged immunoglobulin or T-cell receptor genes by GeneScan analysis or heteroduplex analysis for clonality assessment in lymphoma diagnostics.
Methods Mol Biol. 2013; 971:65-91 [PubMed] Related Publications
The assessment of the presence of clonal lymphoproliferations via polymerase chain reaction (PCR)-based analysis of rearranged immunoglobulin (Ig) or T-cell receptor (TCR) genes is a valuable technique in the diagnosis of suspect lymphoproliferative disorders. Furthermore this technique is more and more used to evaluate dissemination of non-Hodgkin lymphoma and/or the presence of (minimal) residual disease. In this chapter we describe an integrated approach to assess clonality via analysis of Ig heavy chain (IGH), Ig kappa (IGK), TCR beta (TCRB), and TCR gamma (TCRG) gene rearrangements. The described PCR protocol is based on the standardized multiplex PCRs as developed by the European BIOMED-2 collaborative study (Concerted Action BMH4-CT98-3936). Furthermore it also includes the pre-analytical DNA isolation step from various tissues (formalin fixed paraffin-embedded tissue, fresh tissues, body fluids, peripheral blood and bone marrow), GeneScan analysis of labeled PCR products on a genetic analyzer, heteroduplex analysis of unlabeled PCR products, and post-analytical guidelines for the interpretation of the obtained "molecular morphology" patterns.

Lachenal F, Berger F, Cimarelli S, et al.
Primary cerebral angioimmunoblastic T-cell lymphoma.
J Clin Oncol. 2013; 31(5):e64-8 [PubMed] Related Publications

Moroch J, Copie-Bergman C, de Leval L, et al.
Follicular peripheral T-cell lymphoma expands the spectrum of classical Hodgkin lymphoma mimics.
Am J Surg Pathol. 2012; 36(11):1636-46 [PubMed] Related Publications
Epstein-Barr virus (EBV)-infected B cells with Reed-Sternberg-like cell (RS) features may occur in peripheral T-cell lymphomas (PTCLs), especially in angioimmunoblastic T-cell lymphoma. Here, we report 5 patients presenting with lymphadenopathy whose first biopsies demonstrated nodular lymphoid proliferations containing scattered CD30+, CD15+, EBV+ Hodgkin and Reed-Sternberg-like cells, which led to an initial diagnosis of lymphocyte-rich classical Hodgkin lymphoma. However, the uncommon clinical features and/or the occurrence of relapse as PTCL prompted review of the biopsies with expanded immunohistologic and molecular studies and revision of the diagnoses to follicular variant of PTCL (F-PTCL). All cases had atypical small to medium-sized CD3+ T cells that expressed CD10 (4/5) and the follicular helper T-cell (TFH) antigens BCL6, PD1, CXCL13, and ICOS. All demonstrated clonal T cells with a similar pattern in multiple samples from 4 patients. In 2 cases, flow cytometry demonstrated circulating lymphocytes with an abnormal sCD3+, CD4+, ICOS+ immunophenotype. Two patients had a skin rash at presentation, and 1 had B symptoms. Two of the 4 patients treated with polychemotherapy are alive at 3 and 6 years after first diagnosis. These cases highlight how some F-PTCLs may closely mimic lymphocyte-rich classical Hodgkin lymphoma requiring careful assessment of the T cells before rendering the latter diagnosis. The functional properties of TFH cells might lead to the presence of EBV-positive B blasts with RS-like features in TFH-derived PTCL such as angioimmunoblastic T-cell lymphoma and F-PTCL.

Terras S, Moritz RK, Ditschkowski M, et al.
Allogeneic haematopoietic stem cell transplantation in a patient with cutaneous γ/δ-T-cell lymphoma.
Acta Derm Venereol. 2013; 93(3):360-1 [PubMed] Related Publications

Wu D, Sherwood A, Fromm JR, et al.
High-throughput sequencing detects minimal residual disease in acute T lymphoblastic leukemia.
Sci Transl Med. 2012; 4(134):134ra63 [PubMed] Related Publications
High-throughput sequencing (HTS) of lymphoid receptor genes is an emerging technology that can comprehensively assess the diversity of the immune system. Here, we applied HTS to the diagnosis of T-lineage acute lymphoblastic leukemia/lymphoma. Using 43 paired patient samples, we then assessed minimal residual disease (MRD) at day 29 after treatment. The variable regions of TCRB and TCRG were sequenced using an Illumina HiSeq platform after performance of multiplexed polymerase chain reaction, which targeted all potential V-J rearrangement combinations. Pretreatment samples were used to define clonal T cell receptor (TCR) complementarity-determining region 3 (CDR3) sequences, and paired posttreatment samples were evaluated for MRD. Abnormal T lymphoblast identification by multiparametric flow cytometry was concurrently performed for comparison. We found that TCRB and TCRG HTS not only identified clonality at diagnosis in most cases (31 of 43 for TCRB and 27 of 43 for TCRG) but also detected subsequent MRD. As expected, HTS of TCRB and TCRG identified MRD that was not detected by flow cytometry in a subset of cases (25 of 35 HTS compared with 13 of 35, respectively), which highlights the potential of this technology to define lower detection thresholds for MRD that could affect clinical treatment decisions. Thus, next-generation sequencing of lymphoid receptor gene repertoire may improve clinical diagnosis and subsequent MRD monitoring of lymphoproliferative disorders.

Wu RQ, Qiao C, Tong Y, et al.
[Study of immunoglobulin and T-cell receptor gene rearrangements in patients with non-Hodgkin's lymphoma].
Zhonghua Xue Ye Xue Za Zhi. 2012; 33(1):10-5 [PubMed] Related Publications
OBJECTIVE: To investigate immunoglobulin (Ig) and T cell receptor (TCR) gene rearrangements in bone marrow or peripheral blood of patients with non-Hodgkin's lymphoma (NHL), and to explore the potential clinical significance.
METHODS: The Ig/TCR gene rearrangements in bone marrow or peripheral blood of 139 NHL patients were analyzed by using BIOMED-2 multiple primers system and Multiplex PCR assay.
RESULTS: Ig clonality was detected in 85.4% (70/82) of chronic lymphocytic leukemia (CLL), including 46.3% (38/82) IgH rearrangement, 62.2% (51/82) IgK rearrangement and 1.2% (1/82) IgL rearrangement, and in 39.4% (13/33) of other categories of B-lineage NHL (B-NHL), including 33.3% (11/33) IgH and 39.4% (13/33) IgK rearrangements. TCR clonality was detected in 50.0% (12/24) of all definite T-lineage NHL (T-NHL), including 8.3% (2/24) TCRB and 45.8% (11/24) TCRG, no TCRD was detected. The detection rate of gene rearrangements of NHL diversed in different clinical stages \[36.4% in early stage (Ann Arbor stage I and II) and 45.6% in late stage (III and IV)\] and in different degrees of malignancy (40.0% indolent NHL and 45.6% aggressive NHL), but no obvious statistical significance was obtained (P > 0.05). The detection rate of bone marrow invasions of NHL (except CLL) with examinations of bone marrow smear under the microscope was 12.3% (7/57), much lower than the clonality testing (43.9%, 25/57) (P < 0.05). Sensitivity test showed that the sensitivity of malignant clonality testing by multiplex PCR was 3.12% - 6.25%.
CONCLUSIONS: The detection rate of gene rearrangements diverses in different clinical stages and degrees of malignancy of NHL, but the correlation has not been proved in this research. The sensitivity of multiplex PCR-based clonality testing is enhanced with the combination of BIOMED-2 primers system. It is more sensitive than the morphological examinations of bone marrow smear in detecting bone marrow invasions, and may provide a powerful strategy in the routine diagnosis and assessment after treatment.

Yang H, Xu C, Tang Y, et al.
The significance of multiplex PCR/heteroduplex analysis-based TCR-γ gene rearrangement combined with laser-capture microdissection in the diagnosis of early mycosis fungoides.
J Cutan Pathol. 2012; 39(3):337-46 [PubMed] Related Publications
BACKGROUND: The diagnosis of early mycosis fungoides (MF) is a big challenge to dermatologists and dermatopathologists because it lacks specific clinicopathologic features.
METHODS: Fifty-two paraffin-embedded skin samples from 50 patients, including 31 with suspected MF, 10 with typical MF and 9 with benign inflammatory dermatosis (BID), were obtained from our archives. DNA was extracted both by traditional phenol-chloroform method and by the laser-capture microdissection (LCM)-proteinase K approach. The T(VG) /T(JG) , V(2-5) /V(8-12) /JGT(1) and BIOMED-2-TCR-γ primers were used to assess TCR-γ monoclonal rearrangement as measured by polymerase chain reaction (PCR).
RESULTS: In the suspected MF group, clonal TCR-γ gene rearrangements were detected in 11/31 cases (35.5%) by phenol-chloroform DNA extraction and in 25/31 cases (80.7%) by LCM-proteinase K extraction (p < 0.05). While T-cell clonality was detected in 8/10 cases (80%) by the phenol-chloroform method and 10/10 cases (100%) by LCM (p > 0.05) in the typical MF group, no TCR-γ monoclonal rearrangement was detected in the BID group.
CONCLUSIONS: The strategy of multiple PCR/heteroduplex analysis for TCR-γ gene rearrangement combined with LCM increases the detection rate of clonal TCR-γ gene rearrangement in early MF cases and could provide strong evidence to confirm the diagnosis of early MF.

Onozawa M, Aplan PD
Illegitimate V(D)J recombination involving nonantigen receptor loci in lymphoid malignancy.
Genes Chromosomes Cancer. 2012; 51(6):525-35 [PubMed] Free Access to Full Article Related Publications
V(D)J recombination of antigen receptor loci (IGH, IGK, IGL, TCRA, TCRB, TCRG, and TCRD) is an essential mechanism that confers enormous diversity to the mammalian immune system. However, there are now at least six examples of intrachromosomal interstitial deletions caused by aberrant V(D)J recombination between nonantigen receptor loci; five of out these six are associated with lymphoid malignancy. The SIL-SCL fusion and deletions of CDKN2A, IKZF1, Notch1, and Bcl11b are all associated with lymphoid malignancy. These interstitial deletions seem to be species specific, as the deletions seen in mice are not seen in humans; the converse is true as well. Nucleotide sequence analysis of these rearrangements reveals the hallmarks of V(D)J recombination, including site specificity near cryptic heptamer signal sequences, exonucleolytic "nibbling" at the junction site, and nontemplated "N"-region nucleotide insertion at the junction site. Two of these interstitial deletions (murine Notch1 and Bcl11b deletions) have been detected, at low frequency, in tissues from healthy mice with no evidence of malignancy, similar to the finding of chromosomal translocations in the peripheral blood or tonsils of healthy individuals. The contention that these are mediated via V(D)J recombination is strengthened by in vivo assays using extrachromosomal substrates, and chromatin immunoprecipitation-sequence analysis which shows Rag2 binding at the sites of rearrangement. Although the efficiency of these "illegitimate" recombination events is several orders of magnitude less than that at bona fide antigen receptor loci, the consequence of such deletions, namely activation of proto-oncogenes or deletion of tumor suppressor genes, is devastating, and a major cause for lymphoid malignancy.

Keller SM, Moore PF
A novel clonality assay for the assessment of canine T cell proliferations.
Vet Immunol Immunopathol. 2012; 145(1-2):410-9 [PubMed] Related Publications
Polymerase chain reaction (PCR) based clonality assays are an important tool to differentiate neoplastic from reactive lymphocyte populations. A recent description of the canine T cell receptor γ locus identified a large number of formerly unknown genes, and determined the locus topology consisting of 8 cassettes with up to 3 variable (V) genes, 2 joining (J) genes and one constant (C) gene each. Given that these data were not available when existing canine T cell clonality assays were developed, it is likely that they will fail to detect a subset of clonal lymphocyte populations. The objective of this study was to gauge the potential of canine T cell clonality assays to detect all rearranged T cell receptor γ genes and to develop an improved clonality assay. The primer sequences of existing clonality assays were aligned to the reference sequences of all rearranged genes and genes were scored as to the likelihood of being recognized by a primer. All four assays likely recognized subgroup Vγ2 and Vγ6 genes but 3 out of 4 assays were unlikely to detect subgroup Vγ3 and Vγ7 genes. All assays likely recognized Jγx-2 genes, but only two assays were likely to detect most Jγx-1 genes. Two assays had forward primers located as close as four nucleotides to the junctional region. A new multiplex PCR was designed with all primers combined in a single tube. An alternative primer set allowed identification of variable gene usage through gene specific forward primers. The coverage of all rearranged genes facilitated the detection of multiple clonal rearrangements per neoplastic sample. The new assay detected clonal DNA at a concentration of 5% within polyclonal background but detection thresholds were dependent on the gene usage of clonal rearrangements as well as the position of the clonal peak in respect to the polyclonal background. The new multiplex assay recognized 12/12 (100%) of confirmed neoplastic samples as compared to 2/12 (17%) by an existing assay. On a series of 60 diagnostic samples the concordance rate of both assays was 41/60 (68.3%). In 14/60 (23.3%) of the cases, the new multiplex assay yielded a clonal result while the existing assay gave a non-clonal result. In 5/60 (8.3%) of cases, the new assay yielded a non-clonal result while the existing primer set gave a clonal result. These findings suggest that the new multiplex assay has an improved sensitivity over traditional assays and is suited to reduce the rate of false-negative results.

Keller SM, Moore PF
Rearrangement patterns of the canine TCRγ locus in a distinct group of T cell lymphomas.
Vet Immunol Immunopathol. 2012; 145(1-2):350-61 [PubMed] Related Publications
The T cell antigen receptor chains are assembled through a rearrangement process that combines variable (V), diversity (D) and joining (J) region genes. Recently, the entire canine T cell receptor γ (TRG) locus was described. It is arranged in 8 cassettes with up to 3 V genes, 2 J genes and 1 C gene each. However, no data is available beyond the level of sequence analysis. The objective of this study was to identify rearranged genes of the canine TRG locus through experimental analysis and to assess gene usage and patterns of rearrangement in a series of canine T cell lymphomas. Rearranged genes were identified through computational analysis of recombination signal sequences (RSSs), a gene's potential to generate a polyclonal smear, and through sequencing of clonal rearrangements in a series of T cell lymphomas. Out of a total of 32 Vγ and Jγ genes, 21 genes were found to rearrange, 8 genes were considered not rearranged and 3 genes were suspected to rearrange but their status could not be determined definitely. Rearrangements of the canine TRG locus were assessed in a group of canine T cell lymphomas as well as 3 neoplastic T cell lines. An average of 4.6 rearrangements per lymphoma was found suggesting that canine T cells routinely rearrange multiple cassettes per allele. The most commonly rearranged Vγ genes belonged to subgroups Vγ2, Vγ3, and Vγ7. Genes in cassettes 2 and 3 preferentially rearranged within their respective cassettes, while Vγ genes in cassette 7 rearranged to a Jγ gene in cassette 8. There was a strong preference for Vγ2 genes to rearrange to a 3' Jγ gene and for Vγ3 and Vγ7 genes to rearrange to a 5' Jγ gene. This rearrangement pattern coincided with the conservation of the spacer sequence between V and J gene subgroups rather than the topologic location of genes. These data show that highly divergent spacer sequences allow for equally efficient recombination and suggest that spacer sequences can mediate compatibility between V and J genes.

Yang YL, Hsiao CC, Chen HY, et al.
Absence of biallelic TCRγ deletion predicts induction failure and poorer outcomes in childhood T-cell acute lymphoblastic leukemia.
Pediatr Blood Cancer. 2012; 58(6):846-51 [PubMed] Related Publications
BACKGROUND: The absence of biallelic TCRγ deletion (ABD) is a characteristic of early thymocyte precursors before V(D)J recombination. The ABD was reported to predict early treatment failure in T-cell acute lymphoblastic leukemia (ALL). This study aimed to investigate its prognostic value in Taiwanese patients with T-cell ALL.
PROCEDURE: Forty-five children with T-cell ALL were enrolled from six medical centers in Taiwan. Quantitative DNA polymerase chain reaction (Q-PCR) was performed to check the status of TCRγ deletion. The threshold for homozygous deletions by Q-PCR was defined as a fold-change <0.35.
RESULTS: ABD was found in 20 patients [20:45] who had higher incidences of induction failure than those without ABD (P = 0.03; hazard ratio [HR] = 8.13; 95% confidence interval [95% CI] = 1.23-53.77) after multivariate regression analysis. Patents with ABD also had inferior EFS and OS (P = 0.071 and 0.0196, respectively). Multivariate Cox analysis indicated that the association between ABD and overall survival was independent of age and leukocyte count on presentation (P = 0.036; HR = 4.25; 95% CI = 1.10-16.42).
CONCLUSIONS: The absence of TCRγ deletion is a predictor of a poor response to induction chemotherapy for pediatric patients with T-cell ALL in Taiwan. Providing patients with T-cell ALL and ABD with alternative regimens may be worthwhile to test in future clinical trials.

Wang L, Cao ZZ, Qi L
Primary T-cell lymphoma of the urinary bladder presenting with haematuria and hydroureteronephrosis.
J Int Med Res. 2011; 39(5):2027-32 [PubMed] Related Publications
Primary bladder lymphoma, a rare form of non-Hodgkin's lymphoma that is confined to the urinary bladder, is usually of B-cell origin. This report describes an extremely rare case of primary T-cell lymphoma of the urinary bladder. A 45-year-old man presented with haematuria, dysuria and loin pain. Ultrasonography and computed tomography showed a thickened left bladder wall and left hydroureteronephrosis. A diagnosis of primary T-cell lymphoma of the urinary bladder was made on the basis of clinical, radiological and histological findings. The patient, following transurethral resection, was treated with four cycles of CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy with a good response and remains in clinical remission 12 months after treatment.

Carbone A, Della Libera D, Zannier L, et al.
In situ follicular lymphoma associated with overt B- or T-cell lymphomas in the same lymph node.
Am J Hematol. 2011; 86(12):E66-70 [PubMed] Related Publications
In situ follicular lymphoma (FL) is usually an incidental finding in otherwise reactive lymph node [1–3]. However, it may be associated with overt FL, or with lymphomas other than FL or with other malignancies,in other sites or, less commonly, in the same lymph node [2,4–8]. Here we describe two cases of in situ FL, one with concurrent overt FL(Case 1), and one with concurrent peripheral T-cell lymphoma (PTCL),NOS (Case 2) in the same lymph node. Immunohistochemistry, polymerase chain reaction for B and T-cell clonality, and double-staining chromogenic in situ hybridization for BCL2 translocation were performed.In both cases, the in situ FL foci were characterized by strong expression of BCL2 and CD10 in the germinal center B cells of the affected follicles. Case 1 showed the concurrence of an overt B-cell FL with IgH@ rearrangement and expression of B-cell markers, but not BCL2. Case 2 demonstrated the concurrence of a PTCL, NOS with TCRG@ rearrangement and expression of T-cell markers. In conclusion,the association of in situ FL with PTCL expands the spectrum of lymphoproliferations that may coexist with in situ FL and suggests that in situ FL may not behave like a simple precursor for overt FL.

Salgado R, Gallardo F, Servitje O, et al.
Absence of TCR loci chromosomal translocations in cutaneous T-cell lymphomas.
Cancer Genet. 2011; 204(7):405-9 [PubMed] Related Publications
Chromosomal aberrations involving T-cell receptor (TCR) gene loci have been described in several T-cell malignancies. In primary cutaneous T-cell lymphomas (CTCL), the frequency of these aberrations has not yet been well established. We analyzed TCR gene loci (TCRAD, TCRB, and TCRG) status in CTCLs by fluorescence in situ hybridization (FISH). Twenty-five patients with CTCLs were included in the study: 13 Sézary syndromes (SS), six tumoral stage mycosis fungoides (MFt), and six primary cutaneous anaplastic large cell lymphomas CD30(+) (cALCL-CD30(+)). FISH was performed with three break-apart probes flanking TCRAD (14q11), TCRB (7q34), and TCRG (7p14) loci in each case. TCR gene chromosomal rearrangements were not detected in any of the analyzed cases. Gains of TCRB and TCRG genes were observed in 23% (3 of 13) of SS and 50% (3 of 6) of MFt, reflecting the presence of trisomy and/or tetrasomy of chromosome 7 already detected by conventional cytogenetics and array comparative genetic hybridization techniques. TCR loci rearrangements are not frequent in CTCLs; however, we cannot exclude a pathogenic role in these malignancies.

Garcia-Herrera A, Song JY, Chuang SS, et al.
Nonhepatosplenic γδ T-cell lymphomas represent a spectrum of aggressive cytotoxic T-cell lymphomas with a mainly extranodal presentation.
Am J Surg Pathol. 2011; 35(8):1214-25 [PubMed] Free Access to Full Article Related Publications
γδ T cells represent a minor T-cell subset that is mainly distributed in mucosal surfaces. Two distinct lymphomas derived from these cells have been recognized: hepatosplenic γδ T-cell lymphoma (HSTL) and primary cutaneous γδ T-cell lymphoma (PCGD-TCL). However, whether other anatomic sites may also be involved and whether they represent a spectrum of the same disease are not well studied. The lack of T-cell receptor (TCR)β expression has been used to infer a γδ origin when other methods are not available. We studied 35 T-cell tumors suspected to be γδ TCL using monoclonal antibodies reactive with TCR δ or γ in paraffin sections. We were able to confirm γδ chain expression in 22 of 35 cases. We identified 8 PCGD-TCLs, 6 HSTLs, and 8 γδ TCLs without hepatosplenic or cutaneous involvement involving mainly extranodal sites. Two such cases were classified as enteropathy-associated T-cell lymphoma, type II. The other γδ TCL presented in the intestine, lung, tongue, orbit, and lymph node. In addition, we observed 13 cases with mainly extranodal involvement that lacked any TCR expression ("TCR silent"). In all cases, a natural killer cell origin was excluded. In conclusion, the lack of TCRβ expression does not always predict γδ-T-cell derivation, as TCR silent cases may be found. The recognition of γδ TCL presenting in extranodal sites other than skin and liver/spleen expands the clinical spectrum of these tumors. However, non-HSTL γδ TCL do not seem to represent a single entity. The relationship of these tumors with either HSTL or PCGD-TCL requires further study.

Disclaimer: This site is for educational purposes only; it can not be used in diagnosis or treatment.

Cite this page: Cotterill SJ. TRG, Cancer Genetics Web: http://www.cancer-genetics.org/TRG.htm Accessed:

Creative Commons License
This page in Cancer Genetics Web by Simon Cotterill is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Note: content of abstracts copyright of respective publishers - seek permission where appropriate.

 [Home]    Page last revised: 27 February, 2015     Cancer Genetics Web, Established 1999