Larraine Sathicq, 2011, Good Health Issue 09/11 p062-065
Is it in your Genes?
Can you avoid a disease that you’re genetically predisposed to? Larraine Sathicq finds out.
About half of the Australian population will at some time in their lives be affected by a condition
with a genetic basis. But even if you have a potentially deadly illness on many branches of your
family tree, it doesn’t mean you’re staring at a definite diagnosis, and it shouldn’t stop you being
proactive about prevention, says Associate Professor Kristine Barlow-Stewart, director of NSW
Health’s Centre for Genetic Education. “For the majority of conditions, what you’ve inherited is a
susceptibility to a disease or condition,” she says. “To happen they need a triggering factor and,
although we don’t know what all these factors are, there are some like smoking and a poor diet
that we do know about and can avoid.”
Diabetes
Reduce your risk
Exercise regularly. Just 30 minutes of physical activity five times a week and losing as little as five per
cent of your body weight can slash your diabetes risk by more than half. To increase the benefits of
exercise, try resistance training with a milk chaser. A recently published report showed that weight
training helps prevent inflammation-related diseases such as type 2 diabetes. Done regularly, this
type of training reduces your risk for diabetes by building muscle mass and regulating blood levels of
the proteins that trigger inflammation. Researchers in Canada recently found that women who
drank two large glasses of fat-free milk after a weight-lifting session lost more fat and gained more
muscle than those who followed up their exercise with an energy drink.
Drink moderately. A new study suggests that women who enjoy a daily tipple of up to one standard
drink and men who have up to two drinks are less likely to develop type 2 diabetes than those who
don’t drink at all. The 10-year study of over 35,000 adults in the Netherlands found that moderate
drinking can significantly lower diabetes risk even in people who live healthy lifestyles. Among
people who exercise regularly, moderate drinkers were 35 per cent less likely to develop diabetes
than their teetotal counterparts, and among people of healthy weight, drinkers had a 65 per cent
reduced risk compared to non-drinkers.
Heart Disease
There are certain forms of heart disease that may be inherited, says Barlow-Stewart, so if you have
one or more close family members who have been diagnosed with a heart problem before the age
of 55, it’s worth a discussion about risk assessment and genetic testing with your doctor.
Reduce your risk
Live well. That means getting regular exercise, not smoking, maintaining a healthy weight and eating
a diet containing plenty of fresh fruits and vegetables, as well as some omega-3 fatty acids.
Watch your numbers. Cholesterol build-up can clog your blood vessels and lead to coronary artery
disease. Some people inherit a predisposition to high cholesterol and are unable to control it with
normal strategies like diet and exercise, says Barlow-Stewart. The condition is called familial
hypercholesterolaemia (FH). An estimated 80 per cent of Australians with FH are undiagnosed and
may not find out they have it until they develop heart problems. Another major heart risk and
relatively silent condition is high blood pressure, so it’s important to have it checked every time you
go for a check-up.
Reduce job stress. A recent long-term study of more than 12,000 Danish women found that those
who considered their job stress a little too high were 25 per cent more likely to develop ischaemic
heart disease and those who described their work as much too stressful increased their risk by
almost 50 per cent. Rethink that overtime, too. Research involving over 6000 British workers found
that those who did 11- or 12-hour days were 56 per cent more likely to have heart problems than
those who kept normal hours.
Bowel Cancer.
Genetic testing for some rare types of bowel cancer is available, but because the condition is so
common and is also age-related, Barlow-Stewart says it might just be chance rather than genetics to
blame. However, in some people an inherited predisposition to some forms of bowel cancer means
you’ve been dealt a faulty copy of one of the genes that normally protects against bowel cancer. The
more family members affected and the younger they are (under 55 years) at diagnosis increases the
likelihood that you’ve inherited a higher risk yourself.
Reduce your risk
Get tested. All Australians are encouraged to be screened for bowel cancer using the faecal occult
blood test (FOBT) at age 50. The test detects traces of blood in the faeces and may be followed up by
a colonoscopy – a procedure to visually examine the large intestine. If you have a strong family
history, however, Barlow-Stewart says your doctor may recommend having a colonoscopy test when
you are 10 years younger than your youngest family member was at the time of diagnosis.
Up your vitamin D intake. European research involving more than 500,000 participants found that
those with the highest levels of vitamin D had a 40 per cent lower risk of colon cancer than those
with the lowest levels. Vitamin D is stored under the skin and released on exposure to sunlight, so if
you’re not getting enough sunshine, ask your doctor about vitamin-D supplements.
Eat more fish. Especially oily fish like salmon, which is a good source of omega-3 fatty acids. A recent
US study found that people with the highest consumption of omega-3s had half the colon cancer risk
of those with the lowest intake.
Breast Cancer.
For some types of breast cancer, a genetic test can identify faults in BRCA1 and BRCA2 genes, which
you can inherit from either parent, so you’re not just looking at your own mother and sisters but
your grandmother, aunts and cousins on your father’s side, too. “If you have one or more close
relatives with breast or ovarian cancer your own risk may be increased,” says Barlow-Stewart. “Even
so, only five per cent of breast cancers are due to these inherited faulty genes.”
Reduce your risk
Lose weight. A Canadian study of women with a BRCA1 mutation found that those who lost 4.5kg or
more between the ages of 18 and 30 could reduce their likelihood of developing breast cancer
between ages 30 and 40 by 65 per cent. The scientists also concluded that BRCA1 carriers who gain
over 4.5kg during the same period and have two or more children are 44 per cent more likely to
develop breast cancer. The link did not apply to BRCA2 carriers.
Breast feed. Data from the Nurses Health Study involving more than 100,000 women in the US
shows that breastfeeding mums with a strong family history of breast cancer can cut their chances of
getting breast cancer by 59 per cent. And you don’t have to breastfeed forever either, the risk
reduction for women who fed their babies for a lifetime total of three months was the same as for
those who breastfed for three years or longer.
Mental Illness.
The chances of developing a mental illness such as bipolar disorder or schizophrenia is about one in
100, but the risk increases if you have one or more close relatives who are affected. “We have good
data regarding how much higher your risk is if you have conditions like schizophrenia or bipolar
disorder in the family,” says Barlow-Stewart. “We know that if you have a brother or sister
diagnosed with schizophrenia there’s a 10 per cent chance of you developing it, too. If you also have
a parent with schizophrenia your risk increases to 15 per cent.” Having a sibling with bipolar means
your own risk is 15 per cent and if a parent also has bipolar your risk is 20 per cent. Although the
evidence isn’t as strong, genetics may also play a role in depression risk.
Reduce your risk
Be aware. Barlow-Stewart says knowing your risk is higher than average puts more importance on
adopting the tried-and-true prevention strategies like regular exercise, being aware of mood
changes and seeking help when appropriate.
Change your habits. Smoking cannabis can trigger schizophrenia in people who are predisposed to
mental illness and excessive alcohol intake can mask the symptoms of depression. And avoiding
tobacco smoke is especially important during pregnancy – Finnish scientists found that unborn
babies exposed to cigarette smoke are up to 44 per cent more likely to need psychiatric drugs in
adulthood.