Nijmegen Breakage Syndrome
Nijmegen breakage syndrome (NBS) is a rare syndrome characterised by chromosomal instability, probably as a result of a defect in the Double Holliday Junction DNA repair mechanism. It is characterized by microcephaly, a distinct facial appearance, short stature, immunodeficiency, radiation sensitivity and a strong predisposition to lymphoid malignancy. It is caused by a mutation in the NBS1 gene. The name derives from the Dutch city Nijmegen where the condition was first described (Weemaes et al 1981).