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Nijmegen Breakage syndrome: a progress report
C M Weemaes1, D F Smeets, C J van der Burgt
1Department of Pediatrics, University Hospital Nijmegen, The Netherlands.
Abstract:
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.
Insights
Nijmegen Breakage Syndrome (NBS) patients exhibit microcephaly, short stature, and frequent infections. NBS patients show severe immunodeficiency and a higher rate of chromosome 7 and 14 rearrangements and malignancy compared to Ataxia-Telangiectasia (A-T).
Area of Science:
- Genetics
- Immunology
- Pediatrics
Background:
- Nijmegen Breakage Syndrome (NBS) is a rare genetic disorder.
- Clinical and cytogenetic findings in NBS patients are not fully understood.
- Comparison with Ataxia-Telangiectasia (A-T) can provide insights into NBS pathogenesis.
Purpose of the Study:
- To describe the clinical and immunological features of the first 30 NBS patients.
- To analyze chromosomal aberrations in NBS patients.
- To compare the frequency of chromosomal abnormalities and malignancy in NBS versus A-T.
Main Methods:
- Clinical examination of 30 NBS patients.
- Immunoglobulin level assessment.
- T cell function testing.
- Cytogenetic analysis of T lymphocytes for chromosomal aberrations.
Main Results:
- All patients had microcephaly, short stature, and a 'bird-like' face.
- Recurrent respiratory infections were common.
- Immunodeficiency (IgG, IgA, IgG2, IgG4 deficiencies) and T cell defects were prevalent.
- Chromosomal aberrations, particularly involving chromosomes 7 and 14, were significantly higher in NBS than A-T patients (p < 0.0005).
- Eight of 19 patients developed malignancies (7 lymphomas, 1 meningioma).
Conclusions:
- NBS patients present with distinct physical features, severe immunodeficiency, and chromosomal instability.
- The increased frequency of chromosome 7 and 14 rearrangements and malignancy in NBS warrants further investigation.
- NBS appears to have a more severe immunodeficiency and higher risk of malignancy than A-T.