RÉSUMÉ
This study was conducted to estimate the frequency of BRCA1 [1 85delAG] mutation among Egyptian female patients with breast cancer. Forty selected female patients with breast cancer, 80 of their female relatives and 10 healthy females as a control group were included in this study. Result: The age of onset of breast cancer was below 40 years in 25 [62.5%] patients and above 40 years in 15 [37.5%] patients.There were significant differences among the patients regarding the age at menarche before 13 years [P=0.011, P<0.05], onset of breast cancer [P=0.000, P<0.001], parity [P=0.000, P<0.001], first delivery before 30 years of age [P=0.04, P<0.05], breast feeding [P=0.002, P<0.05], and positive family history [P=0.000, P<0.001]. The frequency of BRCA1 [1 85delAG] mutation was found among 10% of the patients group .Eight percent of patients with early onset below 40 years and 13.5% of patients with onset after 40 years were heterozygotes for the mutation. Three percent of patients with unilateral breast cancer, 40% of patients with bilateral breast cancer and 50% of patients with breast ovarian cancer were carrying the mutation. Our results indicated that breast ovarian cancer and bilateral breast cancer patients were likely to have BRCA1 [l85delAG] mutation than in unilateral breast cancer