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

Limited data exist regarding the distribution of gene segments used in T-cell receptor γ gene rearrangements (TCRγGR) in T-cell lymphoproliferative disorders. The reported efficacy of TCRγGR 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 TCRγGR 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 TCRγGR were identified in our lymphoma registry from 1995 to 2001. DNA was obtained from fresh/frozen tissue, cell lysates, or paraffin-embedded tissue. Variable (Vγ) 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 (Jγ) region primers was performed to identify Jγ segments. Sixty cases contained a total of 98 TCRγGR, as some cases have more than one rearrangement. The most frequent gene segment combination involved the Vγ1–8 and Jγ1/2 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 TCRγGR. Our gene segment distribution data emphasize the importance of using a comprehensive set of Vγ and Jγ primers for an optimal detection rate of TCRγGR. Protocols with limited numbers of primers should be reconsidered.