What genetic test is used to prevent hereditary diseases?
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Health is invaluable, and understanding family history and the genetic risks each person faces plays a crucial role in preventing disease and health problems. Through genetic testing, we can better understand our individual predispositions to certain genetic conditions. Knowing this information allows us to make decisions about medical follow-up and lifestyle options.
To decipher our genetic risks, a DNA study is necessary, but which one? There are multiple options and strategies for DNA analysis on the market, with prices ranging from €50 to €1,000. To understand the differences between the tests and select the most appropriate study, you should be aware of the characteristics of the test offered:
1. Does the test only analyze specific variants or does it study the genes in a comprehensive manner?
One of the main differences between genetic tests is the way they analyze DNA: while some options analyze a specific list of common mutations, other tests scan the gene from end to end, identifying any changes in the genome. It is important to keep this fact in mind since, in many cases, the variants responsible for a disease in the family are unique and therefore not included in the lists of common variants.
2. Is this a diagnostic or screening test?
Depending on the technology used to analyze the DNA, the test will be screening rather than diagnostic. In the event of a positive result in a screening test, we will always need to confirm the existence of that genetic variant using a second confirmatory technique.
3. How deep is the coverage of the study?
Coverage depth measures the number of times the DNA has been read. In many cases, the decline in genetic testing prices is offset by the depth of analysis coverage. When I have low coverage depths (for example 18), I cannot be sure that I have read that DNA letter correctly, while high coverage depths (for example >100) allow me to be very sure whether it is an A, C, G or T at that particular position.
Knowing these differences, and if your reason for performing a genetic test is to avoid or prevent the development of hereditary diseases, our recommendation is to perform an exome study .
What is the exome?
The exome is the part of the human genome that comprises exons, that is, the regions of DNA that carry the genetic information necessary for protein synthesis. Although it only represents approximately 2% of the genome, the exome is of great functional importance since it contains the genetic instructions necessary for the synthesis of proteins , the molecules that perform key functions at the cellular level for the proper functioning of organs and tissues.
Due to their great functional importance, these DNA regions are poorly tolerant to changes. For this reason, many genetic variants associated with genetic disorders and inherited diseases are found within the exome. In fact, 85% of the genetic variants responsible for diseases are located in the exome.
To perform an exome study, a biological sample (either blood or saliva) must first be obtained from the patient. The genome must then be isolated and the complete exons of the more than 20,000 genes in the human genome must be sequenced. Once all this information has been generated, the patient’s DNA is compared to the world’s reference human DNA , and all detected changes are recorded.
Approximately, each individual presents about 80,000-100,000 genetic variants with respect to the reference genome . However, many of these changes are what we call population polymorphisms, that is, frequent changes in the population that are neutral and do not pose any health problems. Thus, the data is filtered to obtain information on those rare variants that do impact gene function. These changes in DNA are known as pathogenic or likely pathogenic variants and, depending on which gene they are located in, they will indicate risks for the development of specific diseases.
Exome analysis is a widely used tool for diagnosing genetic diseases and inherited disorders.
Are you concerned about a family history of cancer or cardiomyopathies that run in your family?
We suggest you take an exome test and interpret the results with one of our geneticists during the results explanation visit included in the test.
