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High levels of cholesterol are caused not only by a fat-rich diet but are also based in the activity of a certain gene. Photo: Tinoelf
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Gene Variant Protects Against High Cholesterol
Cardiovascular diseases are the most common cause of death in Germany and often are traced back to heightened levels of cholesterol in the bloodstream. These in turn usually are due to an unhealthy diet. But what is the reason for some people displaying higher levels of cholesterol in their blood although they eat just as healthily or unhealthily and also the remaining conditions are the same? A large-scale international genome study revealed that a certain gene area on chromosome 1 is of significance in this issue.
In co-operation with the University of Aarhus in Denmark, Prof. Dr Thomas Willnow from the MDC in Berlin now explained the function of this gene area in the mouse model and in doing so examined in particular the function of the gene SORT1. The researchers disabled this gene in mice in a targeted manner and found that in spite of a fatty diet these mice had 20 percent less cholesterol in their blood than the mice in the control group. SORT1 contains the code for the protein Sortilin, which in junction with other molecules determines how much cholesterol the liver issues into the bloodstream. The gene SORT1 occurs in various variations, also in humans: "The most common variant is very active, so that the liver releases relatively large amounts of cholesterol. Only about a quarter of the population features a less active variant and this has a certain protective effect, because the liver does not release quite so much cholesterol", explains Willnow. The researchers think that the SORT1 gene could constitute a point of attack for new forms of medication. The aim is to block the release of surplus cholesterol from the liver. In doing so, the target is not the gene directly but the Sortilin it produces. Work on developing such pharmaceuticals has already commenced. Until they are available, the carriers of the rare SORT1 variant have only a partial advantage. Their liver may release less cholesterol into the blood but there are other genes controlling not the release from but the absorption of cholesterol into the liver. Yet even if everything may be optimal, Thomas Willnow from the MDC advises against too inhibited a lifestyle: "Even if one was to find out by way of a genetic test that one had this less active variant, one still should eat healthily and exercise regularly. That is beneficial in every case." How the level of cholesterol is influenced by these gene variants could be found out only because thousands of people volunteered to anonymously submit their genetic data to science. For only on the basis of data from large-scale genome studies researchers can find out in which areas of the genome they are to begin their search in the first place.
