Nijmegen breakage syndrome
Related gene: NBN
Inheritance pattern: Autosomal recessive
Variants in the NBN gene, which codes for a protein called nibrin, cause Nijmegen breakage syndrome (NBS), a chromosomal instability condition. Deficiency of nibrin leads to poor ability to repair DNA. As a result, affected individuals are highly sensitive to the effects of sunlight and radiation, or any substance that can cause breaks in DNA. The inability to repair DNA has many associated complications, including short stature, small head size (microcephaly), distinctive facial features, combined B and T cell immunodeficiency, an increased risk of cancer, and mild intellectual disability. Individuals with NBS have a propensity for infections, particularly sinopulmonary infections, because of the combined immunodeficiency.
Individuals with NBS require the same types of care as those with other DNA breakage syndromes. Immunoglobulin (Ig) replacement therapy can help with the recurrent infections. Health maintenance and cancer surveillance are critically important, as is aggressive management of infections and related problems.