The distribution of gene segments in T-cell receptor γ gene rearrangements demonstrates the need for multiple primer sets

Limited data exist regarding the distribution of gene segments used in T-cell receptor gamma gene rearrangements (TCRgammaGR) in T-cell lymphoproliferative disorders. The reported efficacy of TCR-gammaGR protocols ranges from 60% to greater than 90%. Laboratories reporting a lower detection rate tend to use a limited set of primers. The goal of our study was to provide TCRgammaGR data to demonstrate the molecular biological basis for needing multiple primer sets targeting all gene segments. Sixty cases with a confirmed histological diagnosis of a T-cell lymphoproliferative disorder and TCRyGR were identified in our lymphoma registry from 1995 to 2001. DNA was obtained from fresh/frozen tissue, cell lysates, or paraffin-embedded tissue. Variable (Vgamma) region gene segments were identified using denaturing gradient gel electrophoresis, which was used to select the cases in the study. Capillary electrophoresis using fluorescent-labeled joining (Jgamma) region primers was performed to identify Jgamma segments. Sixty cases contained a total of 98 TCRgammaGR, as some cases have more than one rearrangement. The most frequent gene segment combination involved the Vgamma1-8 and Jgamma1/2 segments. if a single primer set directed at these two segments were used for clinical diagnosis, that pair of primers would only diagnose 67% of cases as positive for TCR-gammaGR. Our gene segment distribution data emphasize the importance of using a comprehensive set of Vgamma andjy primers for an optimal detection rate of TCRgammaGR. Protocols with limited numbers of primers should be reconsidered.