How do you Know if a Test is Valid and Useful?
The validity of a DNA test depends on two parameters: whether the test can correctly detect the absence or presence of a genetic factor or factors which, on the other hand, have been correlated with the predisposition to develop a disease.
Clinical utility refers to whether the genetic analysis that is marketed can really provide beneficial information for the consumer, in order to maintain healthier lifestyle habits.
Not all DNA tests sold are certified by the authorities, which supports the need to interpret their conclusions with caution.
How do you Decide Whether to have a Genetic Test?
Leaving aside the genetic analyses that can be performed in clinical practice, it is possible that we have ever considered buying a DNA test.
These tests are voluntary, and can help us to know a little better the risk or the predisposition to suffer a disease, helping us to improve our lifestyles to reduce the probabilities of contracting a pathology.
In any case, performing a genetic analysis is easy, but interpreting its conclusions is not an easy task, so it is advisable to consult an expert to understand the results and their limitations.
What do the Results Mean?
Companies that commercialize DNA tests make predictions about our characteristics by inferring certain genetic markers.
However, their conclusions should not be taken as definitive. On the one hand, physical traits or even the risk of suffering from a disease depend on multiple genetic factors, which are not always evaluated well or in their entirety in these tests.
On the other hand, the analyses that are made in clinical practice, unlike the tests that are commercialized, are interpreted by experts who also know our medical history and that of our family, which helps to better understand their conclusions.
A positive result can indicate, for example, that a person carries a specific genetic mutation, which can imply a greater risk of suffering from a disease or support the diagnosis of a pathology.
The genetic analyses that are commercialized, however, have a predictive character, since they are generally made before having symptoms of a disorder, reason why frequently they cannot demonstrate a specific risk of a disease because they are not conclusive results.
On the other hand, a negative result shows that the laboratory has not found a change in the genes or chromosomes studied.
From this, it can be extrapolated that this person does not carry a genetic mutation or that he or she does not present an increased risk of suffering from a disease. However, it is also possible that the DNA test has ignored some other alteration that may increase the predisposition to develop a pathology.
In other cases, the results are not informative because changes are detected in the DNA that have not been associated with specific health problems, so it can be understood that it is a variation that does not cause any effect or that it is a mutation of which we do not yet know its impact on health.
Is it Possible to Know our Ancestors?
Before the United States Food and Drug Administration changed its mind about 23andMe DNA tests, the most popular genetic tests analyzed our genealogy.
From these simple analyses it is possible to know some curiosities about our ancestry. In men, studying the chromosome can help us learn more about their male ancestry, while it is possible to evaluate the mitochondrial genome, which we inherited from our mothers, to trace a little better our genealogy.
Some tests evaluate panels of single nucleotide polymorphisms (SNPs), i.e. variations of a single letter of DNA, in order to infer patterns about our ancestry.
These results offer predictions about our genealogy, estimating what percentage of different ethnicities we have. What companies do is make these kinds of estimates by comparing our results with previous databases, so their conclusions may not be conclusive.
Predictions may also be limited by the large number of human migrations: in ethnic groups where there has been little genetic variability, it is easier to infer the results with small changes in DNA.
However, in populations where there have been large variations in the letters of the genetic material, it is more difficult to predict our origin and ancestry solely from individual DNA tests.
On the contrary, genetic studies carried out on large populations help scientists to trace our own history as a species, which has led to a slightly better understanding of human evolution.
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