Since an elevated risk of breast cancer has been also observed among carriers of mutations in the BRCA1, p53 and ATM genes [16, 17], and because these gene products interact with each other and with NBS1 [18], these findings suggest that NBS1 is another gene that might be associated with increased risk of breast cancer in heterozygotes [15]. The gene discussed is BRCA1; the disease is breast carcinoma.