Abstract
I review one aspect of the A-T phenotype, the remarkable and fascinating increase of lymphocytes carrying chromosomal aberrations caused by V(D)J site-specific recombination. The review is organized to first present the facts of V(D)J recombination and the findings in this regard in A-T patients. Other populations that demonstrate similar increases in such chromosomal aberrations are then presented and a hypothesis is offered as to the basis and relevance of these increases vis-à-vis A-T. The contribution of V(D)J recombination to the clonal proliferations and frank lymphoid malignancies seen in A-T patients is briefly discussed. I conclude with some speculative comments extending the observations presented into a more global consideration of a possible function of an A-T gene.