VH AND TCRG gene rearrangements

These PCR assays are routinely used for the identification of clonal B and/or T-cell populations.

The VH assay amplifies the DNA between primers that target the conserved framework and joining regions which lie on either side of an area within the V-J region where programmed genetic rearrangements occur during maturation of all B lymphocytes. The genes which undergo rearrangement are the immunoglobulin heavy chain and light chain genes, with each B-cell having a V-J rearrangement that is unique in length and sequence. Consequently amplification of this region will result in one or two amplicons in a clonal population and a Gaussian distribution of amplicons in normal and polyclonal populations of cells.

The TCRG gene locus includes 14 V genes, 5 J segments and 2 C genes. The TCRG assay, using the same concept as the VH assay, detects the majority of TCR gamma gene rearrangements. As above, clonality is indicated if one or two amplicons result from the assay.

These tests can be used to identify clonal populations of B or T-cells, to determine lineage of lymphomas and leukaemias and to evaluate and assess disease recurrence or residual disease.

The following is an extract from the BIOMED-2 Concerted Action Reports, Leukemia 2007; 21; 201-206.

“In this era of increased attention for quality improvement in medicine, we believe that the introduction of the BIOMED-2 clonality assays lead to a more reliable diagnosis and thus to a better care for patients who are suspected to have a malignant lymphoma.”