BRCA1 and breast carcinoma: The highest risk of breast cancer was found in carriers of the BRCA2/1991del4 mutation (HR = 8.45, 95% CI 0.97 to 73.24) followed by the two BRCA1 mutations A1708E (HR = 6.66, 95% CI 1.57 to 28.38) and 3450del4 (HR = 5.63, 95% CI 1.78 to 17.81), and the BRCA2/3034del4 mutation (HR = 1.50, 95% CI 0.17 to 12.84).