b'TRB Clonality Assay Clonaltiy TestsClinical Information Test Name used to identify DNA sequences specific to clonal gene The human T-cell receptor beta (TRB) gene locus onThese developmentally regulated, programmed generearrangements. Bioinformatics tools facilitate the chromosome 7 (7q34) includes 64-67 variable (V) generearrangements generate combinations that are uniqueTRB clonality assaycharacterization of sequences present at greater thansegments (belonging to 30 subgroups), 2 diversity (D)for each cell. 1Since leukemias and lymphomas originate2.5% of the population. These sequences can be used to gene segments, and 13 joining (J) gene segments, spreadfrom the malignant transformation of individual lymphoidAssay Type track specific clonal populations.over 685 kilobases, making this locus far more complexcells, all leukemias and lymphomas generally shareNext-Generation Sequencing (NGS)than others. Nevertheless, accurate molecular analysis ofone or more cell-specific or clonal antigen receptorIndications for Testingthe TRB genes is an important tool for the assessment ofgene rearrangements. Clonality does not always implyThis test is performed by using the LymphoTrack ordentify clonality in atypical lymphoproliferative clonality in suspected T-cell and some B-cell proliferations,malignancy; all results must be interpreted in the contextLymphoTrack Dx Assay from Invivoscribe. Ias TRB gene rearrangements occur not only in almost allof all of the other available diagnostic criteria. Tests thatdisordersmature T-cell malignancies, but also in about one-third ofdetect TRB clonal rearrangements can be used to helpSupport a differential diagnosis between reactiveprecursor B-acute lymphoblastic leukemias (B-ALL). 1 identify T-cell and certain B-cell malignancies. Method Description lesions and hematologic malignanciesFor detection of the vast majority of TRB geneAssign presumptive lineage in mature monoclonal Lymphoid cells are different from the other somatic cells in the body, as during development the antigen receptorrearrangements, a multiplex master mix targetinglymphoproliferative disordersgenes in lymphoid cells (including gene segments within thethe V, J and D regions is used for PCR amplification.Monitor and evaluate disease recurrenceTRB locus), undergo somatic gene rearrangement. 2 Next-generation sequencing of the PCR products is Interpretation TurnaroundSpecimenShippingStorage Time Requirements Conditions ConditionsAn interpretive report will be5 to 10 1-3 mL of peripheralAmbient or2-8 C up issued indicating whetherbusiness daysblood in Heparin, Cool; do notto 7 days evidence of clonality wasEDTA or ACD freeze (peripheralprior to detected. The report further0.25-1 mL of boneblood or bonetesting provides a summary of the marrow) top 5 merged sequences,marrow in Heparin, including the % total reads, EDTA or ACD Ambient or References 500 ng of previouslyfrozen on dry ice the rearrangement class and 1.JE Miller et al., Molecular Genetic Pathology (2013, 2nd ed.) Springer Science & Business Media 302.2.7.13 and 30.2.7.18. the sequence. isolated DNA(isolated DNA)2.Tonegawa S (1983) Somatic Generation of Antibody Diversity. Nature 302:575-58132 LabPMM Services Catalog 2020|33'