T-cell receptor gamma and delta gene rearrangements in T-cell acute lymphoblastic leukemia in Indian patients.

T-cell acute lymphoblastic leukemia (T-ALL) is a clonal lymphoid malignancy and junctional sequences of rearranged T-cell receptor (TCR) represent the best suitable marker to study clonality in these patients. A sensitive, non-radioactive, and rapid approach of PCR coupled with heteroduplex analysis was used to analyse clonality of TCR gamma and delta gene rearrangements in 26 Indian T-ALL patients. Amongst TCR gamma gene family, VgammaI-Jgamma1.3/2.3 sequences were most utilized (53.9%) while from TCRdelta repertoire Vdelta1-Jdelta1 sequences were preferentially rearranged (23.1%) in these patients. 19.2% of Indian T-ALL patients demonstrated both clonal TCR gamma and delta gene rearrangements along with surface expression of TCRgammadelta. Although the majority of T-ALL patients showed surface expression of TCRalphabeta, the small fraction (19.2%) of TCRgammadelta+ T-ALL represent a distinct subgroup which needs further evaluation.