Preconception genetic testing: towards preventive reproductive medicine

Assisted reproduction technologies have undergone a major change in recent years. While in the past all our efforts were invariably aimed at obtaining better results in terms of the pregnancy rate, today, even though we can say that much remains to be done, we have results that can be described as better than good and solutions, which in the past, would have been unthinkable.

It is therefore time to begin to strive not only for a good result but to practise, insofar as is possible, medicine that is preventive and not just reactive.

Specifically, as far as genetic diseases are concerned, we currently have cutting-edge technologies that allows us to establish the genetic carrier status of the individual’s recessive genetic diseases by analysing a panel of many dozens of diseases. Carrier status does not involve, as is well known, the risk of disease in the carrier but it does with regard to the risk of disease in the offspring, in the event that both parents are carriers of the same set of mutated genes. If we included all known genetic diseases, the entire population would probably be carriers for one or more disease. If we reduce the study to the most serious and frequent diseases, which present themselves at birth or in childhood, with a significantly decreased life expectancy and quality of life, we can say that 40-50% of the general population will be carrying one or more of them.

It is true that the handling and management of these results of a genetic nature is not easy and requires a kind of medical practice where ethical the principles of beneficence and autonomy of patients are respected with the utmost delicacy.

Approximately one year ago, Clinica Eugin decided to launch the expanded carrier screening programme for genetic diseases, both in patients who are initiating an assisted reproduction technique, as well as in our gamete donation programme.

The aim of offering this possibility to our patients is to know in advance the serious genetic disease carrier status and thus take a preventive approach such as performing a PGD associated with its conventional IVF cycle, for example.

In the case of the egg donation programme, these tests allow us to go much further than we could until now. Conventionally, and as a priority, the egg donor is matched to a recipient according to the physical characteristics of the recipient, as well as those of the blood group. The application of the expanded genetic screening test on both the man, who will fertilize the eggs, as well as the donor thereof, allows us to perform what is called “genetic matching.” That is to say, firstly, the donor is selected according to the recipient’s phenotype and, secondly, we verify that the donor is genetically compatible with the semen that we are going to fertilise the eggs with. This will significantly decrease the likelihood of generating diseased embryos. In our case, we provide a test of> 200 genetic diseases, both for our patients as well as those performed on our donors. Applying more targeted genetic analysis and limited to the origins of the individual makes less sense and becomes less accurate. This is because societies are increasingly multi-ethnic and it is more and more difficult for the individual to know their genetic origins with any degree of precision.

This preventive approach enables us to reduce the risk of serious genetic diseases in the offspring. We should not forget that the probability of a pair of gametes matching mutations in the gene for the same disease is around 4%. If this happens, the risk of disease in the child is 25%.

It is important to highlight that the implementation of these expanded genetic tests has been done throughout our entire donation programme. All our donors are tested with this screening. However, the aim of these tests is not to reject donors but, quite the contrary, to manage the results for the benefit of the newborn’s improved health. Applying this test only makes sense if it is also performed on the man whose semen is going to fertilise the eggs. Otherwise, it would have no added value.

Expanded carrier screening tests open up the door to the development of preventive medicine which, until now, was unthinkable for both technical and economic reasons. Now it is up to us health care professionals to decide on which basis we are going to apply them for the benefit of our patients and to learn to manage them without fear but with responsibility. We at Clinica Eugin are confident that this situation no longer belongs to the future but should be part of our present. And that is what we have been doing.

Dr. Amelia Rodriguez
Eugin Medical Director