In conclusion, our study findings suggest important differences between FA genes, indicating that truncating variants in FANCC do not confer a high overall risk of breast cancer unlike PALB2, BRCA1 and BRCA2. Our study does not exclude a role of monoallelic FANCC variants as low-penetrance alleles for breast cancer or as a genetic risk factor for certain breast cancer subgroups. This evidence concerns the gene BRCA1 and breast cancer.