These are distinct from the rare and essentially purely inherited forms of the disease due to mutations in the BRCA1 and BRCA2 genes, which cause between 1 and 3 percent of breast cancers. (decode.com)
Although mutations in several proteins can lead to inherited forms of the disease, nobody knows what triggers the overwhelming number of sporadic cases. (scientificamerican.com)
Scientists have spent much of the past three decades hunting down genes linked to this inherited form of the disease. (discovermagazine.com)