Gene tests for heart disease: perils and promise
Coronary heart disease is the result of arteries furring up and a clot forming (MRSA)
Professor Steve Humphries, London IDEAS Genetics Knowledge Park and University College London.
Ms Eluned Hughes, London IDEAS Genetics Knowledge Park.
Dr Gail Davies, London IDEAS Genetics Knowledge Park and Imperial College London.
Professor Theresa Marteau, King's College London.
The discovery of 'the gene' for a variety of illnesses from breast cancer to schizophrenia is frequently headline news. But do these reports generate unrealistic expectations of how useful these genes are in identifying disease and providing treatment?
'Yes', says Steve Humphries of the London IDEAS Genetics Knowledge Park. 'What is so often misunderstood is the multifactorial nature of these diseases. There is rarely just one gene that increases risk. You are looking at a complex interaction between a number of genes and a whole host of lifestyle and environmental factors: diet and smoking, for example'.
London IDEAS is one of a network of six Genetics Knowledge Parks in the UK directly funded by Government. IDEAS' programme of clinical research, guidance for the public and training for health professionals aims to enable people to make informed choices about diseases for which they are at genetic risk. A particular focus of their work is Coronary Heart Disease (CHD), the leading killer of people in the developed world and a condition for which genetic testing has a potential role.
In some people, early CHD is caused by a single gene defect, such as the disorder Familial Hypercholesterolaemia (FH). About 1 in 500 people have FH, which leads to very high blood cholesterol levels and heart disease risk, and is passed from parents to, on average, half of their children. Genetic testing of relatives of FH sufferers can identify those at risk and ensure they are treated successfully with cholesterol-lowering drugs.
However, most people with a genetic risk of heart disease have inherited several genes, each of which slightly increases their risk. Some of these gene variants are only a risk when other environmental factors are present. For example, UK research has shown a strong interaction between variations in the APOE gene and smoking. Individuals with the variant known as APOE4 are at a higher risk of CHD compared to others, but only if they smoke.