REFERRALS for genetic breast cancer tests more than doubled in the UK as a result of what doctors have dubbed the "Angelina effect".

In May last year, actress Angelina Jolie revealed to the world that she had undergone a double mastectomy to prevent her getting breast cancer.

She took the decision after testing positive for the BRCA1 gene mutation that greatly increases the risk of developing the disease.

A new study has now measured the impact her surprise announcement made on women in the UK.

It shows that in June and July last year the number of GP referrals for genetic counselling and DNA tests for breast cancer mutations increased two and a half times compared with the same period in 2012. The effect was long-lasting, with referrals remaining at twice the previous year's figure from August to October.

Most of the extra women seeking help had a family history of breast cancer.

Professor Gareth Evans, from the charity Genesis Breast Cancer Prevention and St Mary's Hospital, Manchester, who led the study published in the journal Breast Cancer Research, said: "Angelina Jolie stating she has a BRCA1 mutation and going on to have a risk- reducing mastectomy is likely to have had a bigger impact than other celebrity announcements, possibly due to her image as a glamorous and strong woman.

"This may have lessened patients' fears about a loss of sexual identity post-preventative surgery and encouraged those who had not previously engaged with health services to consider genetic testing."

He said such "high-profile" cases often meant women were more inclined to contact family history clinics "so that they can be tested for the mutation early and take the necessary steps to prevent themselves from developing the disease".

He added: "In some cases this may mean a risk-reducing mastectomy, however cancer preventing drugs, such as tamoxifen, and certain lifestyle changes like a healthy diet and more exercise, are also options which many women may consider."

Defective versions of BRCA1 and its sister gene BRCA2 are responsible for about a fifth of breast cancers. Women with BRCA1 have a 60% to 90% risk of developing breast cancer, while BRCA2 increases the risk by 45% to 85%. Both mutations also raise the risk of ovarian cancer.

Under NHS guidelines, women can qualify for BRCA testing if one of the mutations has already been identified in a relative or they have a strong family history of breast cancer.