Your family tree might give you a glimpse into your own future health – but it’s not too late to alter what was once set in stone.
For many health-conscious midlifers, casting an eye over the wellbeing of your parents and grandparents can feel akin to monitoring a ticking time bomb. For as the baby boomers grow older and develop chronic illnesses, the unsettling truth is that this could represent a glimpse into your own future.
Apart from the odd scattering of random mutations which make you a unique being, most of the letters in your DNA come from your parents, grandparents, great-grandparents and so on, going back six generations.
With this comes a myriad of inherited physical or personality attributes. We all owe our looks, inclination towards certain hobbies and, to a certain extent, how agreeable, impulsive and creative we are, to our ancestors. But we also share their frailties, particularly when it comes to the ravages of age-related illnesses.
Earlier this week a study by Oxford University revealed that one of the leading risk factors for developing dementia is a parental history of the disease.
Not so long ago, the only means of assessing your future disease susceptibility was to glance at your family tree. But this is far from accurate as there are few guarantees in genetics. As well as lifestyle factors, most chronic illnesses arise from the cumulative effects of many gene variants across your genome – which can each be inherited from various ancestors – that together combine to increase risk.
Now, the rapidly falling cost of DNA sequencing means that it is possible to get an accurate idea, without breaking the bank. According to Kamal Obbad, who runs the personal genomics testing service Nebula Genomics, which offers whole genome sequencing and the opportunity to find out your disease risk for as little as US$99 ($168), millennials are particularly interested in finding out what the future might hold.
“We find that those most interested in whole genome sequencing are 30 to 40 years old,” he says. “Understanding what your genes say about your predisposition towards certain conditions allows you and your doctor to make smarter decisions about preventative actions to promote health and longevity.”
So for these four chronic illnesses, how can lifestyle changes, preventative testing and even surgery help alter what used to be set in stone?
Cancer
In 2013, Angelina Jolie made an announcement that would change the lives of millions of women around the world. Writing in the New York Times, she explained that she had a faulty copy of a gene known as BRCA1 which gave her an 87 per cent chance of developing breast cancer, and a 50 per cent chance of developing ovarian cancer over the course of her lifetime. Having already lost her mother to ovarian cancer, she was all too aware of the risk.
Over the following two years, Jolie would undergo a preventative double mastectomy followed by breast reconstruction surgery, as well as having her ovaries removed. Increasing numbers of women with a family history of both diseases began opting for the same.
According to Clare Turnbull, professor of Translational Cancer Genetics at the Institute of Cancer Research, London, ovary removal is being increasingly recommended to women with defective copies of either the BRCA1 or BRCA2 gene. This is because ovarian cancer tends to be a much more aggressive disease, with less effective treatment possibilities compared to breast cancer.
“Once a woman completes her family, having surgical removal of the ovaries and tubes is a really effective way of not developing ovarian cancer,” she says. “Ovarian cancer has much poorer outcomes so that’s a much more impactful intervention.”
Over the past decade, large-scale genomic sequencing initiatives mean that we know an increasing amount about the heritability of various cancers. Men can now get genetic testing on the NHS to find out if they have BRCA mutations which place them at an increased risk of prostate or pancreatic cancer.
For diseases such as colorectal cancer, individuals who carry risk genes are eligible for colonoscopies at two-year intervals from the age of 25. “They can also take high-dose aspirin, which is very effective at reducing their colorectal cancer risk,” says Turnbull. “And for women, once they’ve completed their families, we would recommend considering having a hysterectomy.”
But at the same time, simply carrying gene variants does not mean you are guaranteed to get the disease. There is increasing evidence that carrying too much weight or drinking three or more alcoholic drinks per day raises the risk of various cancers, with overweight, post-menopausal women far more likely to develop ovarian cancer.
“As an example, colorectal cancer is only 15 per cent heritable,” says Turnbull. “So 85 per cent of what is causing colorectal cancer is your accrued exposure to environmental factors, many of which are related to diet and the microbiome. So the lifestyle advice relating to minimising ultra-processed foods, exercising and so forth, is clearly the most impactful.”
Heart disease
According to Sir Nilesh Samani, professor of cardiology at the University of Leicester and medical director of the British Heart Foundation, genetics can play a great role when it comes to heart muscle diseases, life-threatening abnormal heart rhythms known as channelopathies and familial hypercholesterolaemia or excessively high cholesterol levels.
“There are some forms of cardiovascular diseases, such as hypertrophic cardiomyopathy and Long QT syndrome, where the inheritance is very strong, so if your parent has it, then your risk of getting the disease may be 50 per cent,” he says. “There is a push at the moment in the UK, to try and screen for familial hypercholesterolaemia as many people are not identified early enough, which leads to preventable heart attacks and strokes.”
Samani’s advice is that if a parent has suffered from high cholesterol, to have your own cholesterol measured on a regular basis, beginning in your 20s onwards. Again, if a parent has died from a sudden heart attack before the age of 60, he says that it could be worth discussing with your GP about having a CT scan of the arteries in your heart, particularly in your 40s and early 50s.
But while genetics can play a bigger role in driving cardiovascular disease, compared to some other forms of chronic illness, through making the arteries more susceptible to stiffening or incurring blockages, adapting your lifestyle can still help.
If heart disease or stroke runs in the family, Samani recommends monitoring your blood pressure, switching to a Mediterranean diet which is lower in meat and higher in fish.
“There are simple things you can do,” he says. “For example, I often see patients in my clinic who are worried about their family history, but they still smoke.”
Arthritis
Genetic factors contribute to around 60 per cent of the risk of rheumatoid arthritis, a chronic inflammatory disease which causes pain in the small joints of the hands and feet, as well as stiffness and swelling.
While the condition severely affects the quality of life of sufferers, and even reduces life expectancy by an average of three to 10 years, any risk posed by your genes can be mitigated through maintaining a healthy weight.
“Think more about healthy eating and putting healthy foods inside your body – for example, eat more fruit, vegetables and grains to fill you up, and try to eat less sugar,” advises Dr Wendy Holden, an honorary consultant rheumatologist and medical advisor for the charity Arthritis Action.
Early signs of rheumatoid arthritis include swelling and stiffness which is worse in the morning and improves with exercise. Holden recommends taking action early and seeking medical advice, because blood tests, ultrasound and MRI scans can catch the condition before it causes joint damage and disability.
The other main form of arthritis is osteoarthritis, with variants in genes which form and maintain bone and cartilage contributes to somewhere between 40 and 70 per cent of the risk.
This condition usually begins after the age of 40 and causes pain and stiffness in the joints. But leading an active life can help reduce risk.
“If you are inactive, start to move more. For example, just walk up and down stairs a few more times every day, and set low goals that you can easily achieve,” says Holden. “If you are already active, move more, ideally at least 30 minutes of moderate activity every day.”
Dementia
In November 2022, the Hollywood star Chris Hemsworth revealed that he carries two copies of a gene variant called APOE4, something which makes him eight to 10 times more genetically predisposed for Alzheimer’s.
While this might sound shocking, the link between Alzheimer’s – and indeed the vast majority of dementia cases – and genes is a highly complex one. Around 25 per cent of the population carry one copy of APOE4 while Hemsworth is in the 2 to 3 per cent who carry two copies, but the vast majority of dementia cases are thought to be related to the consequences of ageing and lifestyle factors rather than genetics.
For example, social isolation, an unhealthy diet, excessive alcohol consumption, poor sleep and lack of exercise are all thought to be bigger contributors to dementia than your DNA.
According to Joyce Shaffer, a psychologist and behavioural scientist at the University of Washington, taking steps to improve your lifestyle in midlife can make all the difference.
“Sleeping for between six and 10 hours per night is important, exercise that includes aerobics, strength building and balance, and trying to engage in forms of new learning such as making music are all things you can do,” she says. “Music can enhance brain chemistry, architecture and performance.”
When Hemsworth found out that he carried two copies of the APOE4 gene, his initial reaction was to step back from acting to spend more time with family. Yet Shaffer says that in reality, one of the best ways to mitigate any genetic risk of dementia is to keep your brain active through continuing to work and participate in projects.
“Stay on the job like the neurologist Howard Tucker, who’s still seeing patients at the age of 101,” she says. “Or write a book like the best-selling author Herman Wouk, who wrote a new memoir at the age of 100. Remaining active through later life in different organisations which interest you, while also providing social interactions, keeps your brain healthy.”
Five questions to ask your doctor
North London GP Semiya Aziz recommends discussing the five questions below with your doctor if you are concerned about your genetic risk of a particular disease because it runs in your family.
- What is my risk of getting the disease likely to be?
- Is there any kind of genetic testing available to see if I’m at risk, and if so, what are the benefits and limitations?
- Is it available on the public system or will I have to pay privately?
- What kind of information can testing give me, and what does the process involve?
- How can knowing about my genetic risk potentially help me?