Genetic early warning for heart disease

Testing for gene variants could predict cardiovascular risk before lipid levels show danger.

Identifying cardiovascular problems before risky lipid levels show could be possible using a panel of gene variants, say US scientists.

Half of the variation in LDL and HDL cholesterol levels is thought to be hereditary.

Now scientists believe that checking for as few as nine gene variants could help doctors to identify those who need help to lower cholesterol early.

The nine single nucleotide polymorphisms (SNPs) - DNA variations in just one nucleotide - are linked to cholesterol.

Levels of these SNPs were assessed in more than 5,000 adults who took part in an epidemiological study in Sweden in the mid-1990s. With the possibility of zero, one or two unfavourable alleles available for each SNP, the potential genotype score ranged from zero to 18.

People scoring six or less had an average LDL level of 3.9mmol/l, compared with 4.4 mmol/l in those scoring 13 or more. Those with a low score had HDL cholesterol levels of 1.6mmol/l, and those with high scores had levels of 1.3mmol/l.

Crucially, the test was also linked to cardiovascular events. Analysis of 10 years' follow-up showed those with a genotype score of 11 or more had a 63 per cent higher risk of a cardiovascular event than those with a score of nine or less.

Despite these promising findings, checking for the nine SNPs was no better than standard risk factor assessment for predicting cardiovascular events. But among people considered to be at 'intermediate' risk on standard measures, the gene test was able to distinguish between elevated or reduced levels of risk, say the researchers.

Study lead, Dr Sekar Kathiresan, from the Massachusetts General Hospital said: 'A panel of polymorphisms could be useful to define who, at a young age, is at risk from a heart attack and to target lifestyle and pharmacological interventions to these individuals.'

Such a test is likely to be available within five years, he added.

N Eng J Med 2008; 358: 1,240-9

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