Mutations in a gene called PALB2 raise the risk of breast cancer in women by almost as much as mutations in BRCA1 and BRCA2, the infamous genes implicated in most inherited cases of the disease, a team of researchers reported Wednesday.

Previous data had indicated that mutations in PALB2 were linked to breast cancer, and many genetic tests already screen for them. But it had not been clear to what extent these mutations raised a carrier’s odds of developing the disease.

Dr. Marc Tischkowitz, an associate professor of medical genetics at the University of Cambridge, and his colleagues studied 362 members of 154 families with PALB2 mutations. None had BRCA1 or BRCA2 mutations, but all had at least one family member with breast cancer and a mutation in PALB2. There were 311 women with PALB2 mutations, of whom 229 had breast cancer, and 51 men with the mutation, of whom seven had the disease.

The results were published in The New England Journal of Medicine.

Over all, the researchers found, a PALB2 mutation carrier had a 35 percent chance of developing cancer by age 70. By comparison, women with BRCA1 mutations have a 50 percent to 70 percent chance of developing breast cancer by that age, and those with BRCA2 have a 40 percent to 60 percent chance.