Interview with Dr. Leyre Larzabal on Cadena SER

Could you explain, in simple terms for those of us who aren't doctors or geneticists, what a genetic diagnostic test is?

Yes, of course. A genetic diagnostic test is a laboratory test that analyzes our DNA—that is, the “instruction manual” that contains all the information necessary for our bodies to function properly. The information contained in that DNA, in regions we call genes, determines each of our physical characteristics, such as eye color or height. Similarly, the information present in our genes determines whether we develop certain diseases or have a predisposition to them.

The purpose of genetic testing is to determine whether a patient has any genetic alterations or “variations” that may be associated with an inherited disease or an increased risk of developing one in the future. These alterations can be inherited from our parents or arise for the first time in the affected individual without any family history.

Given this, when is it appropriate to undergo genetic testing?

Genetic testing is primarily performed when there is clinical suspicion of a disease with a possible genetic basis. In these cases, genetic testing can help provide a more accurate diagnosis and, in some cases, guide the selection of the appropriate treatment.

It is also recommended to undergo these types of tests when there is a family history of a hereditary disease, since genetic disorders can be passed down from one generation to the next. For example, if there have been several cases of the same disease in a family, doctors may order these types of tests to determine whether a family member also carries the same genetic mutation and thus assess their risk of developing the disease in the future.

In addition, genetic testing can be performed on healthy individuals for preventive purposes. A common example is carrier testing, which is conducted before having children to determine whether both partners are carriers of a mutation in the same gene—a situation that could pose a risk of passing on an inherited condition to their offspring. Having this information allows couples to make informed decisions about future pregnancies and, if necessary, consider family planning options.

How exactly is this test performed? What are the steps involved?

To conduct a genetic study, the first step is to obtain a biological sample from the patient. Generally, this sample can be one of two types:

• Saliva, which is collected very easily by asking the patient to spit into a small tube.
• Blood, which is obtained through a quick draw, similar to a routine blood test.

In our case, we work with several partner laboratories in Spain, so depending on where the patient lives, they can visit one of these laboratories to have their blood drawn. If that’s not possible, we’ll send a kit to their home that includes a saliva collection device so they can collect the sample in the comfort of their own home, and we’ll handle the shipping and pickup through a shipping carrier. The patient doesn’t have to worry about a thing.

Once the sample is sent to and received at our laboratory in Oviedo, my colleagues extract the DNA, which is then analyzed to determine whether there are any of the genetic changes or alterations I mentioned earlier that may be linked to a disease or genetic predisposition. Based on the results, a report is prepared and sent to the physician who requested the test or to the patient.

How long does it take for the patient to receive the results after sending in the sample?

The turnaround time for genetic test results depends on the complexity of the test and the technique used to perform it. For simpler tests, results may be available within a few days, whereas for more comprehensive or complex tests—such as whole-exome sequencing, which analyzes numerous genes simultaneously and requires more advanced techniques—the turnaround time is approximately six weeks.

It is very important to us that every patient knows in advance how long their test may take. That is why, during the preliminary genetic counseling session we conduct with them, we explain in detail the type of test that will be performed and clearly inform them of the estimated time it will take to receive the results.

Now that you mention it, what is the purpose of genetic counseling consultations before and after genetic testing?

Genetic counseling sessions are a crucial step when a person is considering genetic testing; they ensure that the patient is fully informed about the entire process so that they can make an informed decision about whether or not to undergo genetic testing.

Before the test, the consultation aims to explain, in simple terms, what a genetic test entails, which test is most appropriate for that particular case, what information it can provide, and what its limitations and implications are. We review the patient’s family and medical history to ensure that the test to be performed is truly the most appropriate one. We answer patients’ questions and clarify their expectations. In short, during this first stage of the process, we provide the patient with as much information as possible to help them understand what type of test will be performed, what results can be obtained, and what each result would mean, so that they can make an informed decision.

After the test, a follow-up consultation is just as important. During this consultation, we review the results with the patient and explain them in clear language so that they can understand what this means for them and their family members. Unlike other laboratory tests, which typically yield numerical results, genetic testing requires specialized training to interpret the findings. Therefore, during this consultation, we help patients understand whether there is an increased risk of developing a particular disease, whether there is a condition that could be passed on to future children, or whether any special medical follow-up is recommended.

In summary, we can say that genetic counseling provides patients with information, support, and guidance at every step of the way, helping them make informed decisions and better understand the results and their implications.

If the test results show a genetic abnormality, does that mean the person will get sick?

This will depend on the specific case we are studying and the DNA mutation that is identified. In some cases, the person undergoing the test has already developed the disease, and genetic testing serves to confirm the diagnosis. In other cases, when the person undergoing the test is healthy—either because there is a family history of the disease or because it is a preventive test—finding a genetic alteration in the test does not necessarily mean that the person will develop the disease. Genes function as instructions, but just because an instruction is altered does not always mean that the problem will appear. In fact, many alterations only indicate a higher probability, not a certainty.

There are several factors at play. Some genetic changes are high-risk, meaning they significantly increase the likelihood of developing the disease, but they do not guarantee that it will actually develop. Other changes are moderate- or low-risk and serve more as a warning sign that it is advisable to be vigilant or undergo specific medical screenings.

Furthermore, genetics is only part of the story. Lifestyle, diet, exercise, the environment, and other health factors also influence whether or not a disease develops. That is why, when an abnormality is detected, genetic counseling is very important. It helps people understand the nature of the risk, what preventive measures can be taken, and what medical follow-up is recommended.

Earlier, you mentioned that genetic testing can be done for preventive purposes. Could you explain that a little more?

Yes, genetic testing can help with prevention in some cases, although it does not in itself prevent a disease from developing. Its value lies in the fact that it can reveal whether a person has a higher risk of developing certain diseases. This information serves as a kind of “warning sign” that helps people make more informed decisions.

For example, if a study shows an increased risk of a disease, doctors may recommend more frequent checkups, lifestyle changes, dietary adjustments, or even specific preventive treatments. This makes it possible to detect the onset of a disease early on, when it is usually easier to treat, or in some cases, to prevent it from developing altogether.

As we have already mentioned, preventive genetic testing can also be very useful before having children, as it allows you to determine whether there is a risk of passing on a genetic disorder and, if so, to assess your reproductive options.

Getting back to genetic testing in general, can it also be done on children?

Yes, genetic testing can be performed on children, but only under a doctor’s recommendation and when such testing is likely to benefit their health. Genetic testing is recommended when a child exhibits symptoms that could be consistent with a genetic disorder; it can help identify the cause of certain health problems, guide treatment, plan for medical follow-up, and anticipate potential complications.

What message would you give to someone who is considering getting a genetic test?

I would tell you not to hesitate to look into the possibility of undergoing genetic testing. Understanding our genetic information can be a very useful tool for managing our health. As we mentioned earlier, the results of genetic testing can be crucial for reaching an accurate diagnosis. This allows doctors to plan more appropriate treatments and establish personalized preventive measures tailored to each patient and their specific needs.

It is very important to remember that, although genetic information can be very valuable, it should always be interpreted with the guidance of healthcare professionals, such as experienced doctors and geneticists. They can clearly explain each step of the process, help you understand the results, and provide guidance on the decisions you need to make, thereby avoiding confusion or unnecessary worry.

How can a patient contact you to undergo genetic testing?

It’s very easy. First and foremost, you can call me at my work number—613-031-849—to tell me what you need. Or, if you prefer, you can also email us at genetica@dreamgenics.com or use the contact form on our website. In either case, we’ll get in touch with you as soon as we receive your information, and we’ll work together to determine your needs so we can help you with whatever you require.