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Lipids (or fat) are essential substances for living cells and organisms. When the body needs for lipids are not met by food (e.g. in the fasting state), the organism can built up its own. Triglycerides and cholesterol are produced by the liver, packaged into lipoproteins called VLDLs and discharged into the blood stream. VLDL can deliver lipids to the right destination with the help of the proteins they contain: apolipoproteins. VLDLs deliver their triglyceride content to the cells (e.g. adipose tissue or muscle) through the interaction of apolipoprotein C2 with lipoprotein lipase (an enzyme breaking down circulating triglycerides) see `hyperlipoproteinemia type I`). Lipoproteins then become smaller particles called remnants, which can be recognized and taken up by cells through the interaction between apolipoprotein E (apo-E) and cellular receptors (key-in-keyhole system). Lipoproteins deliver their contents in cholesterol to the cell. When the apo-E is deficient, remnants fail to enter within cells. They accumulate in plasma and in the arterial wall, favoring the development of atherosclerosis and consequently, of cardiovascular disease (myocardial infarction, stroke) as early as age 40. It is more frequent in men than in women before menopause, and may be aggravated by diet (fat, sugars or alcohol). It is diagnosed on the grounds of specific and transient clinical signs and on a specific profile after lipid testing. Although the disease is inherited its transmission within families departs from classical modes of inheritance. This is why genetic testing is necessary to formally identify the causative factor. Treatment includes a well-adapted diet and hypolipidemic drugs to block the development of arterial lesions and prevent cardiovascular disease. The disorder has been estimated to occur in about 1/10 000 persons in populations. |