The proportion of T-cell antigen receptors in ten patients with ataxia-telangiectasia were compared with normal subjects and patients with other immune deficits at the Departments of Clinical Immunology and Pediatrics, University of Rome, “la Sapienza” Rome, Italy. An increased ratio of gamma/delta bearing to alpha/beta bearing T-cells in ataxia-telangiectasia may reflect both a recombinational defect that interferes with T-cell and B-cell gene rearrangements and an inability to repair damage to the DNA. The criteria for the diagnosis of ataxia-telangiectasia included early cerebellar ataxia, chromosomal instability, and raised alpha fetoprotein levels. There were six boys and four girls ranging in age from 2-18 years. The diagnosis was confirmed by cytogenetic analysis which showed the typical increase in nonrandom chromosomal breaks and translocations. 
COMMENT. In an editorial in the same issue Peterson RDA and Funkhouser JD of the University of South Alabama, Mobile, AL refer to their previously published proposal that essentially all clinical manifestations of ataxia-telangiectasia, including the degeneration of the CNS, are a consequence of a defect in genetic recombination . Elucidation of the molecular abnormalities of the lymphocytes in patients with ataxia-telangiectasia may reveal molecular mechanisms responsible for the cellular differentiation of lymphocytes and other cell systems. The gene responsible for ataxia-telangiectasia has been localized to chromosome 11q22-23. These studies at the molecular level bring new insight in lymphocyte differentiation and the immune disorder that characterizes ataxia-telangiecasia. Absence of tonsils in a child with ataxia should prompt the determination of immunoglobulins.