If Mum has had breast cancer, does that mean you will too? Karen Fittall investigates the genetic link to 10 of Australia’s most common health conditions – and what you can do to stay healthy.
Genealogy is a hot topic these days. But rather than looking up any convicts in your family history, you might be better off finding out whether a particular illness or disease runs in your family. As research shows, many health conditions – some of them life-threatening – have a definite genetic link. Realising you may be at an increased risk, thanks to your family background, means you can take steps to minimise your chances of becoming a statistic.
Because being forewarned is forearmed, we have uncovered the role that genetics play in 10 prevalent diseases. While your genes certainly aren’t the only risk factor associated with these conditions – if it doesn’t run in the family, don’t think you’re off the hook! – we show you how to work out whether your family tree might place you at an increased risk.
Breast cancer
Genetics
Genes are thought to account for between 5 and 10 per cent of all breast cancers. While most women who get breast cancer don’t have a strong family history, some women carry ‘faulty’ copies of genes that put them at an increased risk. Currently, inherited changes in two genes – called BRCA 1 and BRCA 2 – are known to increase breast cancer risk, but other genes may also be involved.
If it runs in the family
If you’ve inherited a faulty gene, the risk of developing breast cancer at some stage in your life rises from 11 per cent (which is the risk to the general population) to between 40 and 80 per cent.
Look out for
While the two genes in question can be inherited from either parent, having at least two close blood relatives (such as your mother, sister, cousin or aunt) on the same side of the family who have been diagnosed with breast cancer, typically before their 50th birthday, considerably raises your risk. If you’re concerned that the BRCA 1 or BRCA 2 gene may run in your family, talk to your GP about genetic testing.
Eat to beat it
Two studies released earlier this year confirmed that a healthy diet may go some way towards reducing breast cancer risk. One study stressed the importance of eating plenty of fruits and vegetables, particularly cruciferous vegies such as broccoli and cabbage, so aim for at least two serves of fruit and five serves of vegetables each day.
Prostate cancer
Genetics
Between 5 and 10 per cent of prostate cancers are genetic. And while no one gene, or single group of genes, has been identified as being responsible for the majority of these cases, researchers have associated the same faulty BRCA 1 and BRCA 2 genes that contribute to an increased risk of breast cancer, with a small proportion of prostate cancers.
If it runs in the family
With a family link, your risk of developing prostate cancer may be as high as double the risk of the general male population. Before age 75, 1 in 9 Australian males – and 1 in 5 by age 85 – will be diagnosed with prostate cancer.
Look out for
Having one close male blood relative (a brother, father, uncle or grandfather) who has had prostate cancer, on either side of the family, is a red flag. A ‘stronger’ family history is thought to exist where a number of male blood relatives have or had prostate cancer. Because the BRCA 1 and BRCA 2 genes account for a small proportion of prostate cancers, a family history of female relatives with either breast and/or ovarian cancer may also be a sign.
Eat to beat it
According to researchers in the UK, eating a 400g serve of broccoli per week may offer a protective effect against prostate cancer. Increase your protection by pairing it with some tomato. Not only have lycopene-rich tomatoes been shown to have a role in reducing the risk of prostate cancer, but eating them with broccoli seems to boost the cancerfighting abilities of both foods.
Heart disease
Genetics
The Heart Foundation recognises genetics as one of the few non-modifiable risk factors for developing heart disease. In fact, research shows that one faulty gene, which leads to an inherited tendency towards high cholesterol, accounts for as much as 10 per cent of heart disease occurring before the age of 55.
If it runs in the family
Research shows that with a family history of heart disease, your risk can as much as double. If you have the faulty ‘high cholesterol’ gene, 100 per cent of men and 74 per cent of women are likely to develop coronary artery disease by the time they reach age 70.
Look out for
A family history of premature cardiovascular disease (striking your father before age 55 or your mother before age 65) is a warning sign. Your risk is also increased if you have a sibling with heart disease.
Eat to beat it
According to the Heart Foundation, a heart-healthy diet means consuming plenty of vegetables, wholegrains, oily fish, fruit, nuts, seeds and legumes. You should limit your intake of saturated fat, which among other things, means choosing lean cuts of meat and reduced-fat varieties of dairy foods. And go easy on the salt!
Type 2 diabetes
Genetics
Your family’s health history is an important risk factor when it comes to type 2 diabetes. So much so that Diabetes Australia–NSW recently launched a ‘Type 2 Diabetes Runs in the Family’ awareness campaign.
If it runs in the family
Your odds of developing type 2 diabetes increase with a family link. If one parent has it, your risk doubles, but if both parents have the disease, your risk is up to six times greater. Having a sibling with type 2 diabetes means you’re four times as likely to develop it yourself.
Look out for
Parents or siblings who develop type 2 diabetes are warning signs, although it’s believed that if your mother has the disease, you’re more at risk than if your father does. The age of diagnosis matters, too – it’s thought that a child has a 1 in 7 chance of developing diabetes if one parent is diagnosed before the age of 50, and a 1 in 13 chance if their parent is diagnosed later in life.
Eat to beat it
The good news is that a healthy diet, combined with regular exercise, can reduce the occurrence of type 2 diabetes by as much as 59 per cent in people who are considered to be at high risk. And don’t skimp on the wholegrains – at least two studies have shown they have a positive effect on insulin resistance.
High blood pressure
Genetics
Along with environmental causes (such as a diet high in salt and a lack of exercise), genetics are recognised as one of the causes of high blood pressure, or hypertension. In fact, it’s believed that between 35 and 65 per cent of high blood pressure is related to inheritable causes. Rather than one particular gene, researchers say it’s more likely to be an interaction of changes in a number of different genes that increases a person’s susceptibility to hypertension.
If it runs in the family
If you have two or more affected relatives, your risk of developing the condition is three times higher than the average.
Look out for
Any close blood relatives who have been diagnosed with high blood pressure should ring alarm bells. And, like diabetes, age plays a factor. A 2008 study found that children with parents who had been diagnosed with high blood pressure before turning 55, had a six-fold higher risk of developing hypertension.
Eat to beat it
Ditch the salt. Avoiding adding it when cooking and when you’re at the table. When buying packaged or processed foods, look for foods with no more than 120mg sodium per 100g. Aim to eat no more than 4g salt (which equals about one teaspoon of actual salt, or 1600mg sodium) a day.
Dementia
Genetics
Family history is believed to play a role in about 25–30 per cent of diagnoses of Alzheimer’s disease. A very small percentage – about 1 in 100, or one per cent – of people with Alzheimer’s have what’s called ‘young-onset’, or ‘early-onset’ familial Alzheimer’s disease, where symptoms begin before 65 years of age.
If it runs in the family
If both parents have Alzheimer’s, nearly 1 in 2 of their children will also develop the disease after the age of 70, says an American study released in 2008. According to statistics, because age is also a natural risk factor for the disease, 25 per cent of the general population over the age of 85 will be affected by dementia to some extent.
Look out for
A family history of the disease, with more than one close blood relative having Alzheimer’s, is significant.
Eat to beat it
Adopting a Mediterranean diet (which includes plenty of fish, vegies, legumes and unsaturated fatty acids, and minimal amounts of saturated fats) has been shown to offer some protection against the risk of cognitive impairment. In fact, people who conscientiously stick to the diet may slash their risk by as much as 28 per cent.
Mental illness
Genetics
DNA plays an important role in mental illnesses, such as schizophrenia and bipolar disorder. And the risk of developing a mental illness increases with the number of affected relatives in your family.
If it runs in the family
Your risk of inheriting a mental illness can rise quite dramatically if family members are affected. For schizophrenia, exhibited by about one per cent of the general population, the risk rises to nine per cent if a sibling has it, 13 per cent if a parent does and 45 per cent if both parents are afflicted. With bipolar disorder, which affects between two and three per cent of the general population, the risk rises to 13 per cent if a sibling has the disease, 15 per cent if a parent does and 50 per cent if both parents suffer from it.
Look out for
A close blood relative, including grandparents, aunts and nephews, who has a mental illness should be a warning sign.
Eat to beat it
Steer clear of processed foods. That’s the message from the University of Melbourne, where researchers discovered that people who eat a diet high in junk foods are more likely to experience mental health issues, such as anxiety and depression. On the flip side, a diet full of vegies, fruit, fish, wholegrains and lean meat may offer some protection against both disorders.
Obesity
Genetics
After height, body mass index is the second most inheritable body feature – in fact, up to 70% of body size may be genetic, according to leading international researcher on the genetics of obesity, Professor Stephen O’Rahilly.
If it runs in the family
Research has shown that an eight-year-old girl is 40 per cent more likely to be overweight if her mother is, while at the same age, a boy is 18 per cent more likely to be heavy if his father is overweight. However, because the link is between children and their same-sex parent, the jury is still out about whether it’s genetics or environmental factors (or both) at work.
Look out for
Overweight parents (especially mothers in connection with daughters and fathers in connection with sons) are worrying signs.
Eat to beat it
There’s no magic formula here – it’s all about making healthy dietary choices instead of eating foods full of saturated fat, being mindful of your total kilojoule intake and keeping an eye on portion sizes. To help you do all that, don’t discount using a food diary, particularly when you’re trying to lose weight. It’s a tactic that can result in double the weight loss compared to someone who doesn’t keep track of what, and how, much they’re eating.
Stroke
Genetics
Your family history can, according to a study released last year, significantly raise your risk of having what’s called an ischaemic stroke. This is the most common type of stroke and occurs when an artery carrying blood to the brain becomes blocked.
If it runs in the family
If you’ve inherited the particular variants of these genes, your risk of having an ischaemic stroke increases by about 30 per cent. This is worrying when you consider the risk of stroke to the general population in Australia is already quite high – 1 in 4 men and 1 in 5 women will have a stroke by the age of 85.
Look out for
A family history should be noted, but take particular care if you’re female and your mother or sister has had a stroke. According to UK researchers, women are 40 per cent more likely to inherit the risk of ischaemic stroke, and it’s more likely to be their mother, rather than father", who has had a stroke previously.
Eat to beat it
American research has uncovered that the higher your intake of ‘bad’ fats, the larger your risk of having a stroke. Women who eat the most dietary fat have a 40 per cent higher risk of ischaemic stroke compared to people who minimise their intake.
Food allergies
Genetics
Heredity is certainly believed to play a role in the occurrence of food allergies. Indeed, some experts suspect the increasing number of people with allergies may be, in part, caused by the fact that the predisposition to developing a food allergy can be passed on through a parent’s DNA.
If it runs in the family
According to research from the University of Michigan, if one parent has a food allergy, there’s a 50 per cent likelihood that their child will, too. If both parents have an allergy, the risk rises to as much as 80 per cent for their children.
Look out for
A parent, or both parents, with a food allergy, or a brother or sister with one, makes you much more likely to develop an allergy.
Eat to beat it
The question of whether avoiding certain foods (such as peanuts, eggs and shellfish) during pregnancy, when breastfeeding and even in a child’s first few years of life can help prevent food allergies is controversial and still being investigated. However, at this stage, according to the Australasian Society of Clinical Immunology and Allergy, excluding certain foods hasn’t been proven to be effective. On the positive side, a 2009 Swedish study showed that boosting your intake of omega-3s during pregnancy and breastfeeding may offer some protection against allergies in children.