Nijmegen Breakage syndrome: a progress report.

We report the findings in the first 30 patients with the Nijmegen Breakage Syndrome (NBS). All had microcephaly from birth, short stature and a 'bird-like' face. Most of them suffered from recurrent respiratory tract infections. Intelligence was normal in half of the patients. Serum immunoglobulins were disturbed in 22/25 patients investigated (IgG deficiency, IgA deficiency, IgG2 and IgG4 deficiency) and T cell defects were found in 23/24 patients tested. The immunodeficiency appears to be more severe than in A-T. Chromosomal aberrations in cultured T lymphocytes occurred preferentially in chromosomes 7 and 14 and at the same breakpoints as in A-T. However, the percentage of chromosome 7 and/or 14 rearrangements was significantly higher in NBS patients than in A-T patients (p < 0.0005). Inv(7) was amongst the most frequently detected aberration in NBS cells as it is in A-T cells. Large clones of cells with rearrangements of chromosome 14 were rare in NBS. Of the first 19 reported patients eight have already developed a malignancy: seven a lymphoma and one a meningioma. It is noteworthy that both the tendency to express rearrangements of chromosomes 7 and 14 and the tendency to develop a malignancy is much higher in NBS than in A-T. Whether there is any causal relationship is as yet unknown.