New breast cancer risk gene discovered

Researchers based at the UK's Institute of Cancer Research (ICR) have discovered that women who inherit a faulty version of a gene called BRIP1 have an increased risk of developing breast cancer. The scientists, who reported the findings at the National Cancer Research Institute conference and in the latest issue of the journal Nature Genetics, say that the discovery could lead to better diagnosis and more tailored treatment in the future.

Most cases of breast cancer are not inherited, but around 5-10 per cent are due to a mutation in genes such as BRCA1 or BRCA2. Whilst most women have a 13 per cent chance of developing the disease in their lifetime, those with BRCA1 or BRCA2 mutations can face up to an 85 per cent chance. Both BRCA1 and BRCA2 make proteins responsible for repairing DNA damage. Researchers have long suspected that there are many other gene variants, which - although they are not linked to clearly inherited forms of breast cancer - can increase a person's risk of the disease.

In the latest study the team studied the BRIP1 gene in 1212 women who had developed breast cancer, but who did not have BRCA1 or BRCA2 mutations, and compared the results with those from 2081 healthy controls. The researchers identified nine BRIP1 mutations in the affected women, and only two in the unaffected controls, showing that the gene is linked to an increased risk of the disease.

Around 0.1 per cent of the British population, or about 30,000 women, have a mutated copy of BRIP1. The researchers estimate that this genetic fault contributes to around 100 cases of breast cancer diagnosed each year in the UK. Lead author Professor Nazneen Rahman said: 'We know there are many more genes still to find before we have the complete picture of the genetic causes of breast cancer, but with each step we are making progress'.

Earlier this year, the ICR team reported the identification of another gene which, when mutated, doubles the risk of breast cancer. They found that the risk of the disease rises to one in six in women with a faulty version of the ATM gene, which is also involved in DNA repair. And in 2002, the researchers reported that mutations in a gene called CHEK2 are also associated with a two-fold increased risk of the condition.