Ninety-five different genes which affect cholesterol levels in the blood have been identified by an international group of experts.
Scientists have achieved an important breakthrough in understanding why some people are born with a strong predisposition to heart disease while others appear to be able to eat fatty food with very little or no increased risk.
The findings could lead to new ways of treating people with naturally high cholesterol – strongly linked to an increased risk of heart disease, the biggest killer in Western countries – with drugs that are tailor-made to suit a person’s particular genetic makeup – so-called “personalised medicine”.
The study, which scanned the entire genomes of 100,000 people from around the world, identified 95 individual locations in their DNA where genetic differences from one person to another conferred a significantly increased risk of higher-than-normal levels of cholesterol in the bloodstream.
Cholesterol
The scientists said that 59 of these genetic mutations were not previously known to them and that, taken together, all of these 95 variations in the DNA of people account for between a quarter and a third of the genetic component of heart disease – the genes that predispose someone at birth to cardiovascular disorders.
It has long been established that heart disease has a genetic component in addition to the well-known environmental influences of diet and lack of exercise, but until now there has been little that scientists could do to tease out the many different genes that are involved in raising the risk of developing cardiovascular problems.
Professor Peter Weissberg, medical director at the British Heart Foundation, said: “The findings in this study, that as many as 95 different genes seem to be involved in regulating cholesterol levels in the blood, illustrate just how complicated the biology is.
“A great deal more research is needed to understand precisely what these genes do and how they interact.
“Although this is just a first step down a long road, the good news is that the more we understand about cholesterol regulation, the more likely it is that new drugs will be developed to prevent heart disease,” he said.
What is cholesterol?
Cholesterol forms part of the outer membrane that surrounds every cell. It’s used to insulate nerve fibres (and so make nerve signals travel properly) and make hormones, which carry chemical signals around the body.
Without cholesterol, your body wouldn’t work – it’s vital to ensure the body’s normal function.
Too much cholesterol in the blood, however, increases the risk of coronary heart disease and disease of the arteries.
Lipoprotein levels
Knowing your cholesterol level isn’t, on its own, enough to tell you your personal risk of heart disease. You also need to know about lipoproteins. These are special molecules that carry or transport cholesterol around the body.
There are three main types:
* Low-density lipoprotein (LDL), often known as bad cholesterol – this carries cholesterol from the liver to the cells and, if supply exceeds demand, can cause harmful build-up of cholesterol
* High-density lipoprotein (HDL), or good cholesterol – this takes cholesterol away from the cells and back to the liver, where it’s either broken down or excreted
* Triglycerides
The greatest danger is when someone has high levels of LDL cholesterol and trigylcerides, and low levels of HDL cholesterol.
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Scientists at Saint Louis University have discovered that microRNA miR-33 may be key to controlling HDL, or’good’ cholesterol levels.
The study was led by Dr. Angel Baldan, assistant professor of biochemistry and molecular biology at Saint Louis University.
Atherosclerosis, the fatty build-up in arteries that causes heart attack, stroke, and peripheral artery diseases, is tied to cholesterol levels, a waxy substance found in the blood.
Statins, drugs frequently prescribed by doctors to manage cholesterol levels, work by lowering LDL, or “bad” cholesterol levels; however, their role in HDL cholesterol is still obscure.
Importantly, HDL has been found to have a protective benefit against cardiovascular disease.
“Atherosclerosis costs lives and takes an enormous toll on our health,” said Baldan.
“If the discovery that miR-33 can be used to raise HDL levels leads to better medications, it will have an enormous impact on our ability to treat heart disease,” he added.
The study examined SREBP-2, an important gene in the body, and zeroed in on the microRNA miR-33, which is expressed within SREBP-2.
Increasing the levels of miR-33 in the liver, scientists discovered, resulted in lower HDL cholesterol levels in an animal model; conversely, turning off miR-33, researchers found, had the effect of raising HDL levels.
Paralleling these results, four separate studies reported similar findings, adding to investigators” hope that better medications may be on the horizon for managing atherosclerosis.
The study was published in a recent issue of Proceedings of the National Academy of Sciences of the United States of America.
A gene network behind hardening of the arteries and coronary heart disease has been identified by a team of scientists from Australia, Europe and the United Kingdom. Their findings expose potential targets for the treatment of heart disease.
Dr Michael Inouye, a postdoctoral fellow at the Walter and Eliza Hall Institute, began the study at the Wellcome Trust Sanger Institute in the UK and completed it earlier this year at the Walter and Eliza Hall Institute. Researchers from Finland’s National Institute for Health and Welfare, the University of Helsinki and Leiden University Medical Centre in The Netherlands were also involved in the study.
Concentrations of cholesterols circulating in the blood are an important predictor of coronary artery disease, the most common form of heart disease. The main pathology of coronary artery disease is so-called ‘hardening of the arteries’, or atherosclerosis, a cycle where cholesterol builds up on the walls of arteries and the body’s resultant immune response leads to more build up.
http://www.sciencedaily.com/releases/2010/09/100915094236.htm
One in six young adults now suffers from high cholesterol, a study has revealed.
This causes fatty deposits to block up the arteries and can lead to heart disease.
The survey of 1,500 adults also found one in five people who know they have the condition are not doing anything about it.
Meanwhile a third of the population are in the dark about their cholesterol level as they have never been tested.
The study was timed to coincide with the start of the UK’s first cholesterol awareness week.
Jules Payne, CEO of Heart UK, said: ‘People are dicing with death by not taking action and making changes to their diet and lifestyle after testing positive for high cholesterol.
‘There is still a lot of work to be done in improving the nation’s knowledge about cholesterol and also eradicating many misconceptions.
‘Even if you are fit, young and healthy and you don’t think you are at risk we would urge everyone to get their cholesterol checked – it can be a silent killer with few visible symptoms.’
High cholesterol is one symptom of the obesity epidemic in Britain. Latest figures have revealed that 32 per cent of women and 42 per cent of men are overweight.
http://www.dailymail.co.uk/health/article-1311554/One-people-35-suffers-high-cholesterol.html