Friday 1 August 2014

Listening to our genes

Knowing that you have a family history of major illnesses can prove invaluable in reducing or even preventing the same risk. Recent interest in double mastectomies as illustrated by the 'Angelina Jolie Effect' shows us that resorting to drastic surgery may be the only solution left for those with a proven predisposition to certain diseases. However, it is not as simple as knowing the genetic risk as this is only part of the story as genetics risk is a complex interplay between the impact of genetic influence, diet, lifestyle and environmental stresses. There may also be gaps in family history as the culture of talking about these issues was not a feature of previous generations. However, working with what we know could prove useful in taking certain steps to prevent illness. So let's examine some of the diseases where there is a known element of genetic influence:

Breast Cancer
Breast cancer has been the most common cancer in the UK since 1997, despite the fact that it is rare in men. It is by far the most common cancer among women in the UK (2011), accounting for 30% of all new cases of cancer in females. Although many women will have an affected female relative, in 9 out of 10 cases, this will be due to bad luck rather than an inherited tendency. Women  at high risk of carrying the breast cancer gene can now be referred to a breast cancer family history clinic. Much can be done to prevent the risk:
  • eat at least 5 portions of fresh fruit and vegetables a day 
  • raise concerns with your GP about your family history worries, particularly if more than one relative is affected by breast or ovarian cancer
  • talk to your GP is a relative has developed breast cancer before the age of 50
  • be breast aware - know what is normal for you
  • go for regular check ups via mammograms from the age of 50 onwards
  • consider stopping HRT once menopausal symptoms have finished
Ovarian Cancer
Although ovarian cancer isn't common, it is the fifth most common cancer among women in the UK (2011), accounting for 4% of all new cases of cancer in females and about 1 in 20 sufferers have a family history of the disease. Blood tests and scans are used to screen women at higher risk and there is an ongoing discussion as to whether these tests should be offered to all women. Ovarian cancer is the fourth most common cancer in UK women, with nearly 7,000 cases diagnosed every year.

The risk of ovarian cancer increases with age, and having a strong family history of the disease also increases a woman’s risk. Women who are overweight or obese or are taking HRT also have a higher risk. Women who have not had children have a greater risk of the cancer than those who have given birth. But taking the contraceptive pill for a number of years reduces the risk of ovarian cancer.

Cancer Research UK is one of the major funders of ovarian cancer research in the UK, investigating ways to prevent, diagnose and treat the disease, funding research into screening programmes which have the potential to detect the disease at a much earlier stage and save lives.

Prevention Strategies
  • the contraceptive pill, pregnancy and breastfeeding cut the number of ovarian cycles and reduce ovarian cancer risk. It is not clear why but hysterectomy surgery may also be protective
  • report any persistent pelvic or abdominal pain, bloating, difficulty eating, feeling full easily or changes in your menstrual cycle
  • talk to your GP is your family history is worrying you, especially if a close relative developed ovarian or breast cancer before the age of 50
  • talk to your GP is you have several relatives affected by ovarian, breast or bowel cancer; a referral to a clinical geneticist is likely
  • until possible links between HRT and ovarian cancer have been clarified, it is best to discontinue with HRT once menopause is finished. Discuss this with your GP
Dementia
Dementia affects 820,000 people in the UK. Around 23 million of the UK population have a close friend or family member with dementia. As well as the huge personal cost, dementia costs the UK economy £23 billion a year, more than cancer and heart disease combined. Despite these figures, dementia research is desperately underfunded. 1 in 5 of us has dementia by the age of 80 with more than half the cases being attributed to Alzheimer's and another quarter due to vascular dementia (poor brain circulation). No cause has yet been found though it may be due to a genetic defect. Lifestyle may also be a factor which could account for vascular dementia. However, there are tantalising new possibilities for predicting the onset.

Research in more than 1000 people has identified a set of proteins in the blood which can predict the start of the dementia allegedly with 87% accuracy. The primary goal of the test was to predict whether people with mild cognitive impairments (usually age-related memory problems) would go on to develop 'full-blown' Alzheimer’s disease over approximately a year. There is currently no cure for Alzheimer’s, so people may question whether an early warning system for the disease is of any practical use. However, having a relatively reliable method of identifying high-risk people who will develop Alzheimer’s could be useful in recruiting suitable candidates for clinical trials investigating future treatments. An important point is that, while the test accuracy rate of 87% sounds impressive, this may not be a good indicator of how useful the test would be if it was used in the wider population.

Prevention Strategies
  • consider genetic testing if 3 or more close relatives have early-onset Alzheimer's
  • eat 5-7 portions of fresh fruit and vegetables a day
  • eat oily fish once a week. Read my blog post on important fats: http://yaso-shan.blogspot.co.uk/2012/07/the-fats-of-life.html
  • watch your weight
  • exercise for 30 minutes a day, 5 days a week
  • cut out smoking and reduce alcohol intake to a moderate level
  • keep your brain active by socialsing, reading, mental challenges etc...; it really is a case of 'use it or lose it'
  • ensure healthy blood pressure levels with a good diet and exercise regimen
  • wear a helmet if you cycle
Bowel Cancer
Bowel cancer is also called colorectal cancer and includes large bowel cancer (colon cancer) and cancer of the back passage (rectal cancer or cancer of the rectum).  The most up to date figures (2011) showed that 41,581 people in the UK were diagnosed with bowel cancer. It is the UK's second biggest cancer killer and the fourth most common cancer. 75% of people who develop bowel cancer have no family link but your personal risk is more than doubled if your parent, child, brother or sister had bowel cancer especially if they developed it young. Discuss your concerns with your GP if there are genuine worries about your risk.

Prevention Strategies
  • limit meat intake especially processed meats such as sausages, burgers and bacon
  • regulate weight by taking moderate exercise on a regular basis; it is thought that exercise may halve the risk
  • eat plenty of fibre
  • make sure you get plenty of folic acid which is found in chick peas, cereals and dark, leafy green greens
  • eat foods rich in selenium such as Brazil nuts and the mineral calcium (found in dairy foods)
  • give up smoking as this is thought to double the risk
  • 5-10 years of HRT use is thought to halve the risk
  • report any changes in bowel habit and rectal bleeding to your GP 
  • request regular screening every 2 years especially if you are over 50
Diabetes
A family history of diabetes increases the risk as does being overweight or 'apple-shaped'. Recently (June 2014), it has been discovered that a genetic susceptibility that gives a tenfold increased risk of developing type 2 diabetes has been discovered. The gene mutation, found in the population of Greenland, will give clues to the different causes of the condition. Several susceptibility genes have been linked with diabetes, meaning that if an individual is carrying one of these genes they face a greater risk of developing diabetes. Complications from this condition include heart attacks, strokes, blindness and kidney failure amongst other symptoms.

Prevention Strategies
  • early diagnosis can reduce the risk of complications so watch put for symptoms such as thirst, fatigue, weight loss, excessive urination or blurred vision
  • keep your weight to within healthy levels for your height and age although this is not always the best indicator of risk. For women, they should aim for a waist circumference below 80cm (31.5in) and for South Asian men (who are particularly at risk), aim for below 90cm (35in) and 94cm (37in) for all other men
Heart Disease & Circulatory Disorders
Coronary heart disease (CHD) include heart attacks and angina, strokes, heart failure, poor circulation, high blood pressure (hypertension) and abdominal aortic aneurysm (AAA) are the biggest causes of premature death and disability in the UK. Genetic risk plays a part but is by no means the sole factor. If a first-degree male relative (e.g. father, brother) has suffered a heart attack before the age of 55, or if a first-degree female relative has suffered one before the age of 65, you are at greater risk of developing heart disease.

If both parents have suffered from heart disease before the age of 55, your risk of developing heart disease can rise to 50% compared to the general population. However, you can protect yourself by taking care of your heart, as the development of cardiovascular disease involves many different factors, not just your family history. Your chance of having a stroke is increased if first-degree relatives have had strokes. If they were young when they had their stroke, then the risk is slightly higher.  Studies have shown that the risk increases if you are a woman and your mother has suffered a stroke.

Studies have shown a genetic component for both hypertension and abnormal blood lipids, factors related to the development of cardiovascular disease.One of the inherited factors is high cholesterol level, known as familial hypercholesterolaemia (FH).  If you have inherited this condition then you will experience a build up of low-density lipoprotein cholesterol in the blood. This can lead to coronary heart disease.

Type 2 diabetes also has a genetic component, so if one of your parents developed the condition you are at greater risk of developing it too.  Type 2 diabetes is another risk factor for the development of cardiovascular disease. In the case of stroke, it is believed that inheriting hypertension is a key factor in the familial link of ischemic stroke. There are several ways you can help reduce your risk of developing coronary heart disease (CHD), such as lowering your blood pressure and cholesterol levels.

Prevention Strategies (NHS recommendations)
  1. Eat a healthy, balanced diet: A low-fat, high-fibre diet is recommended, including plenty of fresh fruit and vegetables (five portions a day) and whole grains. You should limit the amount of salt you eat to no more than 6g (0.2oz) a day as too much salt will increase your blood pressure. Six grams of salt is about one teaspoonful.See below for general guidelines on good nutrition to reduce risk....
  2. Be more physically active: Combining a healthy diet with regular exercise is the best way of maintaining a healthy weight. Having a healthy weight reduces your chances of developing high blood pressure. Regular exercise will make your heart and blood circulatory system more efficient, lower your cholesterol level, and also keep your blood pressure at a healthy level.
  3. Keep to a healthy weight: Your GP or practice nurse can tell you what your ideal weight is in relation to your build and height. Alternatively, find out what your BMI (body mass index) is by using a BMI calculator.
  4. Give up smoking: If you smoke, giving up will reduce your risk of developing CHD. Smoking is a major risk factor for developing atherosclerosis (furring of the arteries). It also causes the majority of cases of coronary thrombosis in people under the age of 50. Research has shown you are up to four times more likely to successfully give up smoking if you use NHS support together with stop-smoking medicines, such as patches or gum. 
  5. Reduce your alcohol consumption: If you drink, stick to the recommended guidelines. The recommended daily amount of alcohol for men is three to four units a day and two to three units for women. Always avoid binge drinking.
  6. Control blood pressure: by eating a healthy diet low in saturated fat, exercising regularly, and, if required, taking the appropriate medication to lower your blood pressure. Your target blood pressure should be below 140/85mmHg. If you have high blood pressure, ask your GP to check your blood pressure regularly.
  7. Keep your diabetes under control: If you are diabetic, you have a greater risk of developing CHD. If you have diabetes, being physically active and controlling your weight and blood pressure will help manage your blood sugar level. If you are diabetic, your target blood pressure level should be below 130/80mmHg.
  8. Take any medication prescribed for you
General Guidelines on a Healthy, Balanced Diet
There are two types of fat: saturated and unsaturated. You should avoid food containing saturated fats because these will increase your cholesterol levels. A low-fat, high-fibre diet is recommended, including plenty of fresh fruit and vegetables (five portions a day) and whole grains. You should limit the amount of salt you eat to no more than 6g (0.2oz) a day as too much salt will increase your blood pressure. Six grams of salt is about one teaspoonful.There are two types of fat: saturated and unsaturated. You should avoid food containing saturated fats because these will increase your cholesterol levels.

Foods high in saturated fat include:
  • meat pies 
  • sausages and fatty cuts of meat 
  • butter 
  • ghee, a type of butter often used in Indian cooking 
  • lard 
  • cream 
  • hard cheese 
  • cakes and biscuits 
  • foods that contain coconut or palm oil
However, a balanced diet should include a small amount of unsaturated fat, which will help reduce your cholesterol levels. Foods high in unsaturated fat include:
  • oily fish 
  • avocados 
  • nuts and seeds 
  • sunflower, rapeseed, olive and vegetable oils
You should also try to avoid too much sugar in your diet as this can increase your chances of developing diabetes, which is proven to dramatically increase your chances of developing CHD.

Useful Links:
Alzheimer's Society: http://www.alzheimers.org.uk/
Cancer Research UK: http://www.cancerresearchuk.org/
British Heart Foundation: http://www.bhf.org.uk/
Diabetes UK: http://www.diabetes.org.uk/