This preliminary study in 54 BC patients from BRCA1 and BRCA2-negative BC families with elevated cancer risk identified candidate BC predisposing PDAVs (known as well as unknown) in 30 genes; PALB2, BARD1, CHEK2, RAD51C, FANCA, RINT1, EXO1, RECQL4, CCNH, MUS81, TDP1, DCLRE1A, DCLRE1C, CD96, CYP1A1, DHCR7, DNAH11, ESCO2, FLT4, HPS6, MYH8, NME8, TTC8, ASPH, C17orf80, FAM111B,GRAMD2, ZNF534, SP100 and USP45. The seven last genes of this list were not connected to the cancer process so far. The gene discussed is CYP1A1; the disease is breast cancer.