Unusual T cell clones in a patient with Nijmegen breakage syndrome.

The rare autosomal recessive Nijmegen breakage syndrome is characterised by severe immunodeficiency, microcephaly associated with mental retardation, and typical chromosomal rearrangements in peripheral T lymphocytes. This syndrome, though similar to ataxia telangiectasia, does not exhibit the neurological and cutaneous signs of this disorder. We report here the first patient with Nijmegen breakage syndrome ascertained in France. Chromosome analysis detected, in addition to the specific aberrations, two clonal T cell proliferations which do not involve the usual bands 14q11.2 and 14q32.1.