Marrying blood relatives is responsible for up to 10 per cent of Type 2 diabetes cases in British Asian communities, a new study suggests.
Experts have long known that south Asian communities are more at greater risk of developing diabetes, accounting for eight per cent of all diagnosed cases, despite making up just four per cent of the population.
But it was unclear whether the genetics or lifestyle factors were driving the increased prevalence.
Many south Asian communities marry within their families, often to second cousins or closer, a practice known as consanguinity, which can leave children at risk of genetic problems.
To find out whether consanguinity was having an impact on health, experts from the Wellcome Sanger Institute and Queen Mary University of London analysed genetic data from more than 400,000 people in Britain.
Researchers found 12 diseases and disorders linked to consanguinity including Type 2 diabetes, asthma and post traumatic stress disorder.
The team said blood-related marriages accounted for approximately 10 per cent of Type 2 diabetes cases among British Pakistanis and around three per cent of cases among British Bangladeshis.
It is also likely to be responsible for eight per cent of asthma cases in British Pakistanis and two per cent in British Bangladeshis.
Daniel Malawsky, first author of the study at the Wellcome Sanger Institute, said: “While consanguinity has a smaller role in common diseases compared to other factors, it is still essential to understand its specific influence on health in these communities.”
In the study, around 33 per cent of British individuals of Pakistani and Bangladeshi descent, were offspring of second cousins or closer, compared with just two per cent of individuals of European descent.
Marrying a close relative
Marrying a close relative can be a problem because it raises the chance of passing on harmful gene mutations that run in families.
A previous study of British Pakistanis found that one in 16 babies born to parents who are first cousins have a congenital anomaly compared to one in 38 of children of unrelated parents.
British Pakistanis and Bangladeshis are known to have a four-to-six-fold increased risk of developing Type 2 diabetes compared to individuals of European ancestry.
But the team said that the health risks of consanguinity should be balanced alongside the positive social benefits of the practice, such as family bonding, and said that a bigger impact was coming from other lifestyle factors, such as lack of exercise, smoking and being overweight.
Coun Ahsan Khan, chair of the Genes & Health community advisory board and councillor at Waltham Forest, said: “This work underscores the significance of culturally sensitive approaches in health research, acknowledging the delicate balance between social benefits and any potential risks.
“The research team actively engaged community members, taking into account our traditions, cultures, and religious practices.
“By empowering people with the knowledge to make informed health decisions, we can help tackle the health disparities in our communities, especially in diseases like type 2 diabetes.”
The team said that the aim of the study was not to “pass judgment on the practice of consanguinity, but to guide scientists as to what kind of studies to conduct in the future to better understand these diseases and the biology underlying them, to help develop treatments”.
The research was published in the journal Cell.