A gene variant known to increase the risk of breast and ovarian cancer has been identified in people of Orkney ancestry.
A new study suggests that one in 100 people with grandparents from Orkney have a specific mutation of the BRCA1 gene.
It turned out that most of them traced their family ancestry to the island of Westray.
It is believed to be the first time such a geographic ancestral link has been established within the UK.
The researchers also discovered the specific Orkney gene variant in smaller numbers in genetic testing in the UK and even the US.
Previous research has found that women of certain ethnic backgrounds, such as Ashkenazi Jews, also have a high percentage of a specific BRCA gene variant.
In the UK, about 1 in 1,000 people have a BRCA1 mutation, which can put women at a higher risk of ovarian and breast cancer.
The BRCA genes are present in every person, both men and women, but when an error occurs in one of them, it can lead to DNA damage and cause cells to become cancerous.
People with a genetic variant have a 50% chance of passing it on to their children.
Awareness of the faulty gene emerged a decade ago when Hollywood actress Angelina Jolie underwent a double mastectomy after discovering she had a BRCA1 variant.
The operation would reduce her risk of breast cancer from 87% to 5%.
However, the NHS advises that risk-reducing surgery is not the only option.
It also advises awareness of breast changes, annual breast exams and MRI scans can help detect breast cancer, while lifestyle changes such as healthy eating and exercise “can sometimes reduce the risk”.
There is currently no reliable screening test for ovarian cancer, it adds.
Analysis by Laura Goodwin, BBC Scotland Science and Innovation Correspondent
Identifying this variant – BRCA1 V1736A – is the culmination of 25 years of clinical research by Prof. Zosia Miedzybrodzka, the director of the NHS Grampian Clinical Genetics service.
At the time, the breast cancer screening center began to detect an increase in the number of families they saw and wanted to know why.
As genetic testing grew, the team saw the same gene variant appear over and over and began to mistrust its significance.
By talking to patients about their origins, the link was made with Westray, an island off the Orkneys with only 600 inhabitants.
BRCA1 V1736A probably originated at least 250 years ago in a founder from Westray.
So far, 37 women of Orcadian descent have been identified with the variant.
Some will never develop cancer, but others have opted for risk-reducing surgery.
20 people have been found to have the gene variant who don’t yet know they carry it.
They were among more than 2,000 volunteers who provided genetic data to the Orcades (Orkney Complex Disease Study) study.
The design of the investigation at the time meant that information would not be made public.
The team behind it has now asked the Research Ethics Committee for permission to contact the identified women to tell them they have the BRCA1 gene variant.
Prof Jim Wilson from the University of Edinburgh, who led the study, said: “In a person here on this island hundreds of years ago this variation happened in a BRCA 1 gene and now we find many descendants both in Westray and further afield in Scotland and further.
“I think this is the most important thing I’ve ever really discovered. It will immediately benefit society as a whole.”
‘It’s important that we know’
Former nurse Linda Hagan was born on Westray and lived there most of her life.
Her parents and grandparents and most of her ancestors were also from the island.
Linda, 69, told the BBC her younger sister died of breast cancer four years ago.
She should get her genetic screening results soon.
Linda has three daughters and said it would be hard to think she would have passed the gene variant on to them.
“But it’s important that we know and hopefully something can be done about it,” she said.
Grandparents from Westray
The latest research from the universities of Aberdeen and Edinburgh has been published in the European Journal of Human Genetics.
The study looked back at the 80 grandparents of the carriers of the BRCA1 variant identified in the Orcades genetic study and found that 60% came from Westray.
Further ancestral ties to the island stretched back to the early 18th century.
The Orkney population is only 22,000, but there are people with shared ancestry around the world and the researchers said they should get targeted testing for the variant.
Currently, the test is available in Scotland to those who know a direct family link to the gene or have a family history of ovarian or breast cancer.
Plans are underway for a small pilot trial that will offer testing to anyone living in Westray with a Westray-born grandparent, regardless of family history.
If the pilot is successful, the long-term goal is to offer the test to anyone in Scotland with a Westray-born grandparent who wants it.
The NHS Grampian genetics clinic has a helpline for questions about the gene variant linked to breast and ovarian cancer for people with grandparents from Orkney. The number to call is 01224 553940. Questions by email can be directed to gram.orkBRCAgene@nhs.scot
GPs cannot help with gene testing and questions about this research and next steps should be directed to the helpline.