This gene was an appealing candidate because of (i) its central role in the formation of the A-complex and it’s critical functions during HR repair, (ii) its implication in BRCA1 recruitment to DNA double-strand breaks, (iii) its interaction with the proteins encoded by the two known breast cancer susceptibility genes BRCA1 and BABAM1 (MERIT40) and (iv) its identification as a breast cancer susceptibility gene in Finnish breast cancer families. The gene discussed is BRCA1; the disease is breast cancer.