It emerged this week that actress and director Angelina Jolie chose to have a double mastectomy, because she carries a gene called BRCA1, which greatly increases her chances of developing breast cancer. Here’s your quickfire science on the story:
Pete - Angelina Jolie carries a mutation in the BRCA1 gene, which stands for breast cancer susceptibility gene one.
Elena - BRCA1 is among a class of genes known as tumour suppressors, along with another gene which predisposes to breast cancer, called BRCA2.
Pete - These tumour suppressor genes encode proteins which are involved in the control of cell division, as well as in the repair of damaged DNA.
Elena - When changes, or mutations, happen in these genes, the resulting proteins may lose their protective function, and so DNA damage can accumulate and cell division may become uncontrolled. This can lead to the development of cancer.
Pete - Mutations in BRCA1 and BRCA2 are passed down through generations, and when a parent carries a faulty version, each of their children has a 50:50 chance of inheriting it.
Elena - Not all people with the faulty BRCA1 or BRCA2 genes will go on to develop cancer, but women with it are around 5 times more likely to develop breast cancer than those without. They’re also at a higher risk of other forms of the disease, including in the ovaries.
Pete - Men with harmful mutations in these genes are also more likely to develop breast, prostate, and pancreatic cancer.
Elena - People with a family history of breast cancer can be genetically tested to find out if they carry the BRCA1 or BRCA2 mutations. This involves a blood test, which looks for the defective changes.
Pete - There are a number of options for those who carry the mutations. Angelina Jolie opted for a double mastectomy, where most of the tissue is removed from both breasts, reducing her risk of cancer here to 5%.
Elena - Alternative treatments include using tamoxifen, a drug which blocks oestrogen receptors in cells. This female hormone encourages the growth of breast cancer cells, so blocking it reduces the chances of getting the disease.