NBN是抑癌基因，编码蛋白是Mre11-Rad50-Nbs（MRN）复合物的组分，参与DNA双链断裂传感和修复。该复合物激活激酶ATM（共济失调毛细血管扩张症突变）和ATR（ATM和RAD3相关）以启动DNA损伤应答，并且自身被ATM磷酸化。该复合物具有DNA核酸酶活性，这对刺激修复很重要。MRN复合物的激活使得G2/M细胞周期检查点对DNA损伤作出响应。NBN突变与Nijmegen breakage综合征相关。在胆管癌、肝、前列腺癌、淋巴瘤、白血病、成神经管细胞瘤和其他癌症中均发现了NBN基因。NBN的突变和拷贝数改变可能导致对辐射的敏感以及特异性抑制DNA损伤的抑制剂敏感（括聚（ADP-核糖）聚合酶（PARP）抑制剂）。

NBN gene encodes a component of the Mre11-Rad50-Nbs (MRN) complex involved in DNA double strand break sensing and repair. The complex activates the kinases ATM (ataxia telangiectasia mutated) and ATR (ATM- and RAD3-related) to initiate DNA damage response and is itself phosphorylated by ATM. The complex has DNA nuclease activity important for stimulating repair. Activation of the MRN complex enables the G2/M cell cycle checkpoint response to DNA damage. The complex is also important for genomic integrity at telomeres, replication forks, immunoglobulin gene loci during rearrangements, and DNA breaks formed in meiosis. Activation of repair mechanisms include non-homologous end joining and homologous recombination repair. NBN mutation is associated with the Nijmegen breakage syndrome, characterized by increased cancer incidence, microcephaly, growth retardation, immunodeficiency, and ionizing radiation sensitivity. Mutations have been found in cholangiocarcinoma, liver, prostate cancer, lymphoma, leukemia, medulloblastoma, and other cancers. Mutations and copy number alterations in NBN may lead to susceptibility to radiation and specific inhibitors related to DNA damage including Poly(ADP-ribose) polymerases (PARP) inhibitors.

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