Ataxia-Telangiectasia — Clonal Growth of Translocation Lymphocytes

Abstract

A clone of lymphocytes marked by a chromosome translocation was followed in a patient with ataxia-telangiectasia over a period of 52 months until death at the age of 23. The translocation involved both chromosomes 14. Initially, the patient had a small proportion (1 to 2 per cent) of lymphocytes with the translocation, markedly reduced response to phytohemagglutinin and increased chromosome breakage. Later studies showed increasing proportions (25 to 46 per cent) of translocation lymphocytes, more vigorous response to phytohemagglutinin and less chromosome breakage. The translocation lymphocytes gradually became the main (56 to 78 per cent) population. Data on this and other patients with ataxia-telangiectasia suggest that mutant clones of lymphocytes with specific translocations sometimes arise and proliferate, perhaps representing a step toward the lymphoid neoplasia to which such patients are predisposed. Lymphocyte clones for ataxia-telangiectasia may thus be analogous to chronic-myelogenous-leukemia cells, which also contain an apparently specific chromosome translocation. (N Engl J Med 289:286–291, 1973)