Heterozygous NBS1 splicing mutation (IVS11+2insT) detected in sporadic gastric, colorectal and lung cancers led to defects in crucial binding to Mre11, Mdc1 and BRCA1, and caused impaired ATM phosphorylation in response to low-dose irradiation in the heterozygous state [27]. Here, BRCA1 is linked to lung cancer.