Three mutations (BRCA1 IVS5+3A>G, 2626–2627delAA and BRCA2 6503–6504delTT) were found in 41 sporadic patients with early-onset breast cancer and one mutation (BRCA1 E1221X) in two sporadic patients diagnosed with both breast and ovarian cancer. Here, BRCA1 is linked to breast carcinoma.