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High cholesterol can lead to familial hypercholesterolaemia – one of the most common genetic diseases leading to abnormally high blood cholesterol levels. In Poland, the problem may affect up to 160 thousand. people. The disease is associated with a 40-fold higher risk of death from coronary artery disease in people under the age of XNUMX. In the most severe forms of the disease, symptoms appear as early as childhood, and patients die of a heart attack before their twenties.
High cholesterol and hypercholesterolaemia
Familial hypercholesterolaemia is one of the most common genetic diseases conditioned by the inheritance of a single, defective gene. This is an example of a condition known as an autosomal dominant disease. Normally, every person has 46 chromosomes (23 pairs) in his cells, two of which are the chromosomes that determine our sex (X and Y chromosomes), while the rest are the so-called autosomal chromosomes. There are genes on each of the chromosomes. We receive one version of a given gene from each of the parents. If the disease is inherited predominantly, it means that it is enough to inherit one version of the defective gene to develop the disease. A sick person has a 50% chance to pass the disease on to their offspring. People who inherit one abnormal version of the gene and who have the second version of the gene normal are called heterozygotes. On the other hand, people who have both versions of the gene abnormal are homozygotes.
In the case of familial hypercholesterolaemia, the most common damage (mutation) in the gene that determines the proper production and function of the LDL cholesterol receptor (the so-called low-density cholesterol or colloquially “bad” cholesterol) occurs. LDL-cholesterol-binding receptors are found on the liver cells, and by trapping particles in the bloodstream, they enable them to be further processed, which prevents the build-up of cholesterol in blood vessel walls and other organs. The works of Joseph Goldstein and Michael Brown, who in the 70s conducted intensive research on cholesterol metabolism in the body, identifying receptors – including the LDL cholesterol receptor – played a key role in the description of the disease and the mechanisms leading to it. process. In 1985, these scientists were awarded the Nobel Prize for explaining these phenomena. In familial hypercholesterolaemia, as a result of a mutation in the LDL receptor gene, cholesterol is not removed from the blood by the liver cells, which increases its concentration in the blood and causes excess cholesterol to accumulate in various organs of the body. This accelerates the development of atherosclerosis and related life-threatening complications such as heart attacks and strokes.
High cholesterol – statistics
It is estimated that one person in five hundred has at least one defective version of the gene (is heterozygous), while one person in a million inherits two mutated versions of the gene (is homozygous). This means that in Poland, the average family doctor looks after several families with this disease. Unfortunately, according to reports from the World Health Organization, at least half of the patients remain undiagnosed. The most dramatic course of the disease is observed in homozygotes. High cholesterol levels are found in them after birth and may exceed the normal limit by up to six times. This leads to the appearance of atherosclerotic changes in the arteries and valve defects (most often the aortic valve), which causes the symptoms of ischemic heart disease before the age of 10. A fatal heart attack can occur in a 30-year-old, and untreated children usually do not live up to the age of 20. The course of the disease is chronic in heterozygotes. Abnormal LDL cholesterol levels can be detected in childhood, but symptoms of atherosclerosis usually only appear in young adults. Nevertheless, the risk of dying from coronary heart disease in people over the age of 100 increases 50 times compared to the healthy population. Men have a 50% risk of a heart attack before the age of 10. In women, the onset of these life-threatening events is delayed by about 15-50 years. In addition to the symptoms of coronary artery disease, in patients with familial hypercholesterolaemia, high blood cholesterol levels lead to the formation of the so-called yellows (also known as yellow tufts), which are a build-up of cholesterol in various tissues of the body. The formation of jaundice in the area of the skin, around the eyes, elbow and knee joints and in the tendons – most often in the hands and feet, including the Achilles tendon – is very characteristic. In an ophthalmological examination, 50% of patients under the age of XNUMX (heterozygotes) show the presence of cholesterol deposits in the cornea – the so-called corneal rings.
Hypercholesterolaemia – symptoms
The disease is suspected on the basis of symptoms (increased atherosclerotic lesions at a young age, presence of yellow tufts and corneal rings), abnormally high cholesterol levels and family history (early occurrence of coronary heart disease and heart attacks in 300st and 190nd degree relatives). Blood tests show the most common elevated levels of total cholesterol and its LDL fraction, with usually normal or only slightly elevated triglycerides. The cholesterol level that should be considered is XNUMX mg / dl for total cholesterol and XNUMX mg / dl for LDL cholesterol. However, it should be remembered that such disorders of the fat metabolism may be a consequence of other, more common diseases such as diabetes, kidney disease or hypothyroidism. Similar disorders may also result from the use of certain medications, including antiepileptic drugs, glucocorticosteroids or contraceptives. Hence, after excluding all other causes of abnormal cholesterol levels and collecting a detailed family history, a genetic test detecting a mutation typical of familial hypercholesterolaemia is decisive. Unfortunately, the diagnosis of the disease is most often made when complications occur (heart attack or stroke). Hence, it is crucial to detect the disease as early as possible, which would enable the examination of family members of the patient before they develop the life-threatening complications of elevated cholesterol levels. This is all the more important as it is known that early initiation of a widely available blood cholesterol-lowering treatment is essential for improving the health of patients with familial hypercholesterolaemia and reducing the rate of fatal complications.
How to Treat High Cholesterol?
Treatment depends on the severity of the disease and the risk of fatal consequences of atherosclerosis, which is also influenced by other factors (e.g. smoking, obesity and other comorbidities). In the homozygous form, treatment is difficult and requires a very aggressive approach. Already in early childhood, drugs that lower cholesterol – statins are used. However, such a procedure is often not sufficient. Then the procedure of choice is to purify the blood of LDL cholesterol circulating in it – the so-called LDL apheresis (a list of centers offering this type of treatment in Poland is available at http://www.hipercholesterolemia.pl/index.html). A drug called mipomersen, which in 2010 entered the final phase of clinical trials, is a great hope for patients with this most severe form of the disease. In heterozygous patients, it is mainly started by changing lifestyle and eating habits, reducing the amount of dietary cholesterol, and introducing cholesterol-lowering drugs (statins, fatty acid binding resins, and ezetimibe). In refractory cases, LDL apheresis is used. The last resort is liver transplantation. When ischemic heart disease develops, it is necessary to implement its full treatment.
Read more:
- Cholesterol without secrets
- Cholesterol “likes” young people