Inheriting a damaged version of a gene called CHK2 nearly doubles a woman's chance of developing breast cancer, according to a study published in the journal Nature Genetics. Scientists believe the discovery may eventually bring improved genetic testing for breast cancer and could lead to new ways of treating and preventing the disease.

A faulty version of CHK2 appears to be one of a number of genes that can combine to increase the risk of breast cancer, according to the study, a collaboration between researchers at The Institute of Cancer Research and the University of Cambridge, and colleagues in the Netherlands.

Scientists already know that faults in the BRCA1 and BRCA2 genes greatly increase the chance of developing breast cancer, but these only account for about 2 per cent of cases. They believe inherited risk of breast cancer is more often caused by a combination of genes, each with a modest effect on risk. The new study suggests that a faulty version of CHK2 is one such gene.