A BRCA1 or BRCA2 mutation was seen in 15 of 564 cases of DCIS (2.66%) and in 24 of 4702 controls (0.51%; OR = 5.33, CI 95% 2.78–10.22, p < 0.0001). The gene discussed is BRCA1; the disease is ductal breast carcinoma in situ.