Cambridge (Massachusetts, USA): “Asharq Al-Awsat”
Results of home genetic testing machines reveal only limited information about the risks their users face, of exceptionally high levels of cholesterol or harmful blood clots.
Statistical figures indicate that nearly 30 million Americans have used genetic testing machines that are sold directly to consumers, such as 23andMe and Ancestry.
At a time when some of those who use these tests feel simply curious about their ethnic heritage, many are paying additional sums to know the extent of their body’s vulnerability to exposure to certain diseases and conditions. But the question: Can the results of those tests tell you any useful information about your risk of developing heart disease, the number one killer in the country?
With regard to coronary artery disease in the heart, which is considered by a large difference from others, the most common case of heart disease, the answer is “perhaps”, according to Dr. Pradeep Natarajan is director of cardiology prevention at Harvard University’s Massachusetts General Hospital. “Genetics is just one aspect of a person’s risk, while lifestyle habits such as smoking, diet and exercise play a bigger role,” he added.
For now, traditional risk factors, such as cholesterol and blood pressure, remain the best way to begin assessing a person’s risk of developing coronary heart disease, which in turn is the root cause of most heart attacks.
Coronary heart disease usually results from various copies (or variants) within many genes, but occasionally arises from variants of a single gene. This applies to familial hypercholesterolemia, a monogenic condition that affects about one in every 250 adults and causes an abnormally high total cholesterol levels, sometimes reaching 500 milligrams per deciliter or more.
Cholesterol and thrombosis The
majority of genetic health tests sold directly to consumers do not scan the entire genome of the body, but rather focus their attention on specific genetic variants associated with specific diseases or health conditions. The results include information about many conditions associated with problems with the heart vessels.
For example, 23 & Me and Ansstrei provide information about “familial hypercholesterolemia” as well as the state of hereditary thrombophilia (thrombophilia).
A genetic test report may indicate that you do not carry any of the 24 genetic variants associated with the genes for “familial hypercholesterolemia”. However, there are now more than 2000 genetic variants considered to be the cause of this pathology. For hereditary hypercoagulability, there are at least 22 variants, but the available tests examine only two of them.
This means that you may still have one of the many variants not included in the test, explains René Pelletier, a genetic counselor at the Preventive Genomics Clinic at Massachusetts General Hospital. She explained this idea to her patients using the example book. “The information you get from the genetic matrix is similar to what you learn from quickly reading a book looking for spelling errors,” she said. You might spot some errors, but you will likely miss many of them. In contrast, the tests inside the clinic in which you work depend on reading every letter of every word and monitoring all spelling errors.
– Check results
On the downside, if a home test suggests that you have one of the genetic variants, it is important that you follow up with a doctor to get a clinical test to verify the results, according to Dr. Natarajan. Attention should be paid in this regard to the fact that the level of control over the quality of test equipment that is sold directly to customers varies from one device to another, and false positive results are also common (which means that the test device indicates that you have certain genetic variants when in reality your body is devoid of them).
Some companies provide customers with the ability to view “raw” genetic data, which can be downloaded and sent to a third-party service. After that, these companies draw up a report that includes copies not included in the original report. However, this report is also not considered accurate and reliable.
Therefore, if you want advice about your risk of developing heart disease, a home test is useless. And if one of your relatives suffers from heart problems before the age of 50, you should ask your doctor about how long you can be referred to a counselor in the field of genetics.
The dangers of genetic variants on the heart
> In an effort to improve efforts to make predictions about heart disease, scientists are searching for genetic signals, relying on methods of dealing with the DNA chain on a large scale. As with many cases, coronary heart disease is hereditary, which means that a number of different genes are associated with it. Many of these genes play a role in regulating blood pressure, cholesterol and blood sugar.
Thousands of different sites in the DNA chain (called genetic variants) can influence the level of risk of a heart attack in middle age, and individuals may have zero variants, or one or two copies of each variant. And while some genetic variants increase your risk, others reduce it. Thus, computing a person’s variables together provides a measure of genetic risk.
To this day, studies based on these genetic calculations offer modest improvements in the predictions of someone’s risk of developing cardiovascular disease in middle age, says Cardiologist Pradeep Natarajan and Associate Professor of Harvard School of Medicine. However, these accounts may be useful if they are exploited at an early stage in life.
On his part, Dr. Pradeep suggests that knowing the risks a person faces at a younger age may encourage them to adopt and stick to healthier behavior patterns, which may include early use of preventive drugs. Studies are still underway to test this hypothesis.
Harvard Health Mission, Tribune Media Services.