DNA testing can do much more than prove kinship or solve a crime. Your DNA can tell you a lot about your health, your body weight, your athletic performance and your susceptibility to certain diseases. What genetic tests are there and when are they of interest to you? We explain.
What are genes?
But first some explanation of DNA and genes. The human body consists of about fifty billion cells. Almost every cell has a nucleus containing the chromosomes. A healthy human being has 46 chromosomes. On each of these chromosomes is DNA - the genetic code - wrapped. If you look at that very closely, you can see the double DNA helix as often seen in pictures of DNA.
The DNA contains the blueprint of the body. In it are written instructions what each cell has to do and has to produce. The instructions are divided up into smaller segments, each dealing with a specific process. We call these segments the genes. For example, the pigment gene determines which pigment has to be made for the eyes, resulting in blue or brown eyes. The code is made up of four different elements called the letters C, G, A and T. Human DNA contains six billion letters. If your DNA code were a book and you wanted to read this book aloud, it would take you a hundred years.
Errors in the genes
When an egg cell is fertilized, the DNA of the father and mother is combined into a new, unique code. A new human being. Subsequently, each time a cell divides, the DNA code is copied. With fifty billion cells and DNA containing six billion letters, you can imagine that things sometimes go wrong. It is estimated that each of us has about two thousand genetic defects. We call them polymorphs if they are more common and 'mutations' if they are rare. You can inherit them from your parents or they can occur during your lifetime. They can occur spontaneously or through exposure to radiation or certain substances.
- Radioactive radiation
- UV radiation
- Mutagenic substances such as soot or smoke
- Copy errors
Consequences of mistakes
Most errors in genes are relatively harmless. They can even be useful. Without mutations we could not have evolved as humans into what we are today. But sometimes genetic defects do have a negative effect. If the enzyme gene is defective, for example, the body absorbs too much iron. This results in iron deficiency disease, a disease with serious health damage that can even be fatal. So a small change in our genetic code of three billion letters can cause a serious defect.
Not all mutations are equally serious, but they can, for example, make our eyes worse, reduce the effectiveness of our immune system, or make our legs shorter or longer. There is a multitude of negative genetic variants that can affect our bodies and each of us has different combinations. Therefore, everyone has their own genetic talents and their own risks for diseases.
What kind of genetic testing exists:
1. Diagnostic genetic research for rare diseases
About 80% of rare diseases have a genetic cause. Take, for example, haemophilia or a certain metabolic disease. If, for example, someone suffers from kidney failure at an early age, this may be grounds for genetic testing. If it is known which genetic mutations can cause such a disorder, tests can be carried out to find out. The patient then receives a diagnosis, which can be very valuable to him or her. Even if there is no treatment for the disorder.
We speak of a rare disorder if it occurs in less than 1 in 2,000 people. One rare disorder can also be caused by several genetic defects. It is therefore not logical to test this type of gene in everyone. There are six thousand different known genetic diseases. There are genetic tests for three thousand of these.
These tests are usually quite expensive. Usually around five hundred euros to test a gene.You can also order these tests from us, but these tests are usually carried out and paid for by regular health care. You can also contact your doctor for this.
2. DNA research into common diseases; polymorphism
Common abnormalities in genes are called polymorphisms. In contrast to mutations, these occur frequently. When only a single letter deviates from a gene, we call it a Single Nucleotide Polymorphism - SNP. The majority of SNP variants have no effect on health. Only two thousand of the ten million known SNPs affect our health. We give two examples.
Lactose Intolerance is a common gene abnormality. The enzyme lactase is required for the absorption of milk or milk products in the intestine. This enzyme cuts the lactose into smaller pieces which can be absorbed and thus form energy for the body. This is very important for babies because it gives them energy from their mother's milk. The instruction to make this enzyme is written on the lactase gene. In a large part of the world population this gene is switched off as one gets older. Simply because humans originally only drank milk as babies or children, not as adults. However, five out of six people in Western Europe have an abnormality in the lactose gene that causes them to continue to produce lactase at an advanced age. So this SNP prevents lactose intolerance from occurring. It is not a variant that causes disease, but something that is beneficial.
One gene abnormality that does cause harm is the SNP responsible for the iron deficiency disease. There's a gene that makes you absorb iron from food. That's good, because you need it. But too much iron is harmful. That is why the gene also regulates that you do not absorb too much of it. A genetic variant in this gene can disrupt this process. In that case, too much iron is absorbed. Iron increases in the blood over the years. At first you do not have any symptoms, but then you get joint pains, you are susceptible to infections, your immune system weakens. You develop diabetes. Eventually your liver is damaged and it is fatal if you do not get treatment.
A doctor will usually find that these symptoms are indicative of hemochromatosis, the medical term for iron deficiency disease. A genetic test can then confirm that there is a genetic abnormality. You will then receive therapy, but the disease that has already developed will continue to exist. This usually reduces your life expectancy. If this disease runs in the family, a genetic test can be done at an earlier stage to prevent damage.
The way medication works in our bodies is also influenced by our genes. Medications usually do not work the same for everyone. Some people have side effects, which can even be fatal, while in other people the medications are perfectly safe. There are certain genes that determine how these medications are converted in our bodies.
For example, you take a pill. The medicine enters your body. Then the drug is recognized in the body as something that shouldn't be there, because drugs are chemicals that the body thinks shouldn't be there. So the liver provides enzymes that recognize the drug, modify it, and remove it from the body through the kidneys. This enzyme comes from an enzyme gene.
The prescription for taking medication takes this system into account. Antibiotics, for example, need to be active in your body for a long time. That's why you have to take them at regular intervals. So that you compensate for the amount that your own body keeps breaking down. When the function of these breakdown enzymes is disturbed due to a genetic defect, the amount of antibiotics in the body builds up to a dangerous, sometimes even deadly, level.
A genetic test can provide insight into how medications work for you.
Why is it that some people can eat whatever they want without gaining an ounce? While someone else - so to speak - only has to look at a cookie to become fat? Overweight and obesity are also determined by genetics.
If you have a fatty meal, the body recognises that there is too much fat in the gut. Fortunately, we have a gene that stops the absorption of fat as soon as you have extracted enough energy from the meal. The rest of the fat remains in the gut and is then excreted from the body.
In some people, however, this gene is defective. In these people, all the fat is absorbed. The fat that is not used, is stored in the body for the future. And that, of course, quickly leads to obesity.
Scientific studies have shown that if you feed someone twice as much fat, some people gain weight as you'd expect, and others don't because they just don't absorb it. So if you want to lose weight, it's good to know how your body handles fat or carbohydrates.
We can use DNA testing to find out how your body handles food, how much of each of these substances is absorbed.
Healthy food is important. We hear that everywhere these days. You should eat lots of fruit and vegetables, and little fat. But it is not true that these health advices apply to everyone. Again, genes play an important role.
Through nutrigenetics it is analyzed whether someone can't tolerate lactose, can't digest wheat or suffers from iron accumulation. Food that is very healthy for some people can be very bad for others. Nutritional recommendations should actually be made personal for everyone, because everyone is genetically different. Everyone has different risks, different disease risks, different strengths and weaknesses.
Nutrigenetics looks at what your genetic variants are and how you can adjust your diet to ensure you are getting the right nutrients.
Sports really bring out whether you have the right genes to really excel. You can train all you want but only those who have the optimal combination of genes reach the top.
Are you more of a strength athlete or is your strength endurance? There are two genes that influence that. For example, we can have two ENDURANCE genes, we can have one ENDURANCE gene and one POWER gene or two POWER genes. If someone has good genes for fast reactions and sprinting, you're going to be very tired from a marathon. Fourteen percent have a double set of ENDURANCE genes. They can run a marathon very well, but they are bad at sprinting.
So genetic testing can tell us everything about:
- rare diseases;
- standard genetic tests;
- common diseases;
- processing of medication;
- talent and aptitude for sports;
- body weight;
- effects of healthy eating.
They are divided into three different groups.
- Lifestyle Analysis. This is not about diseases, it is about optimizing body weight or sports. It is general information about the body.
- Medical analyses often used for preventive purposes, but also for diagnostic purposes.
- Research on rare diseases, mostly of diagnostic nature*.
Many rare diseases are not treated or are treated incorrectly because of a lack of diagnosis, resulting in permanent damage to health. So actually prevention is important. When there is a defect in the family you can test your children early so damage can be limited or prevented. Parents-to-be and future parents can also be tested to see whether they are carrying a certain disorder.
Our laboratory network carries out tests in all three categories. However, the most interesting are medical tests where you still have a chance to improve your health. We can help people stay healthy, even if you are at genetic risk. Lifestyle analyses also help people maintain their body weight.
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