Scientists have discovered a gene that doubles the risk of some women developing breast cancer.

Faults in the BRIP1 gene increase the risk of developing breast cancer in women with a family history of the disease.

Researchers at the Institute of Cancer Research studied the gene in 1,212 women with breast cancer, and compared the results with 2,081 healthy women. The women with breast cancer had a family history of the disease, but did not carry the most common breast cancer genes, BRCA1 and BRCA2, which cause a quarter of hereditary cases. The study found that women carrying the faulty BRIP1 gene had an increased risk, from one in 12 to one in six by age 70.

The findings, published in the journal Nature Genetics, could lead to better prevention and more closely tailored treatment for the disease.

Some 41,700 women and 300 men in the UK are diagnosed with breast cancer every year, and more than 12,400 die from it.

A quarter of breast cancer cases occurring in families are thought to be due to genetic faults. Hereditary cases account for 5 per cent of all new breast cancer cases each year.