Gene found to double risk of heart attacks.

Scientists have identified a set of rare gene mutations that may increase the risk of early heart attacks.

Researchers from the Broad Institute and Massachusetts General Hospital in the USA and other institutions, sequenced the exomes of around 10,000 men and women, half of whom had early heart attacks aged under 50 and 60 years old respectively.

The findings revealed that those with mutations in the APOA5 gene had around a two-fold increased risk of a heart attack. The mutated versions of the gene led to increased levels of triglycerides, a type of fat, in the blood.

The researchers also identified mutations in the LDLR gene, involved in the transport of LDL (or 'bad' cholesterol) in the blood. High levels of LDL have long been associated with heart attacks.

'Our APOA5 result tells us that beyond LDL levels, which are well known to contribute to heart attack risk, abnormalities in triglyceride metabolism also play an important role', said Dr Sekar Kathiresan, a senior author of the study. 'This gives us an important window into the biology of the disease and also suggests potential new avenues for therapeutic development'.

High triglyceride levels in the blood have been associated with heart attacks since 1973, but their role has been poorly understood. The researchers explain that this study, along with a previous report which indicated that mutations in APOC3 (another lipoprotein gene) had a protective role against heart disease (reported in BioNews 759), brings triglycerides back into focus.

The large-scale nature of the latest study allows for a more definitive association to be made, the researchers claim, leading to their conclusion that abnormal triglyceride activity is an important risk factor for heart attack at any age.

'We simply wouldn't have made this critical connection without our careful and disciplined approach to whole exome sequencing and subsequent data analysis', said Dr Stacey Gabriel, a co-author of the study and director of the Broad Institute's Genomics Platform.

Heart attacks are responsible for millions of deaths throughout the world every year. Only around five percent of people suffer from heart attacks at an early age, but the first sign of illness in this group of people is often the heart attack itself, which can result in severe disability and often death.

Last month, another study from the Broad Institute found that mutations on the NPC1L1 gene were associated with lower levels of LDL cholesterol and a lower risk of heart disease (reported in BioNews 780).

The latest study was published in Nature.