BRCA2 and Klinefelter syndrome: Various risk factors have been proposed for MBC, including BRCA2 gene anomalies [10], Klinefelter's syndrome [11], a genetic background such as a familial history of breast cancer, hormonal abnormalities due to obesity or testicular disease (cryptorchidism, mumps, orchitis, orchiectomy), exposure to radiation [1-4,9].