Genetic Compatibility Test
(Genetic Matching)
The Genetic Compatibility Test, also known as Genetic Matching, is a technique that allows us to decrease the transmission of genetic disorders to our children as we are able to detect whether the mother or the father carries some type of mutation (abnormalities in a particular gene).
Of all the genes in our bodies, we are all bound to have some with mutations.
Both partners of the couple can be tested if both provide their gametes, or alternatively a donor, providing an egg and/or sperm, and the other partner of the couple can be tested.
What are recessive diseases?
These mutations may or may not affect our health. Recessive disorders manifest themselves when both parents carry the same disease-causing mutation. Although these patients show no symptoms nor have any family history of the disorder, they are known as carriers. This is possible even when they have no prior family history.
We all have gene abnormalities, but by taking this test we can find out whether our abnormalities could cause our children to have a disorder.
If both partners are carriers of a gene mutation linked to a recessive disorder, there is a 25% chance that their child will have that disorder although neither of them do. When both parents have the same mutation, there is a 25% chance that their child will be born with that disorder. In addition, there is a 50% chance that their children will also be carriers of that disorder which may appear in future generations.
How many diseases can the Genetic Compatibility Test detect?
At Clínica Tambre, we study 320 genes with 32,749 variants responsible for 368 genetic disorders that may develop in children of seemingly asymptomatic parents. The test includes severe prevalent disorders and rare disorders that affect 1 in every 100,000 babies born.
It also includes the most common disorders in paediatric emergencies as well as neonatal and intrauterine death. For such cases we analyse 552 genes linked to 448 recessive disorders, focusing heavily on severe childhood-onset recessive disorders.
After testing both parents, the information is cross-matched (matching) to verify whether both are carriers of the same recessive disorder because, if that were the case, they would have a 25% higher chance of passing the disorder on to the embryo.
What happens if an incompatibility is detected?
In cases with a result of high genetic risk, in addition to genetic counseling, in vitro fertilisation (IVF) and preimplantation genetic diagnosis (PGD) are required to select those healthy embryos and therefore avoid the birth of an affected child. In certain cases, a sperm or egg donor can be a solution.
In the case of a gamete donation, if the result was not ideal, the donor would be changed to minimise the risk of having a sick child. It is important to point out that, although the risk is reduced to a minimum after doing the test, there is no guarantee since there is always a risk that “de novo” mutations or a genetic disease that is not part of the test may appear.
Results
LOW GENETIC RISK: Parents have a low risk of transmitting one of the diseases included in the panel. The two biological parents do not share variants in the same gene. Furthermore, the woman is not a carrier of a variant of the studied genes linked to the X-chromosome.
HIGH GENETIC RISK: Parents have a high risk of transmitting some of the diseases included in the panel. Either because both parents are carriers of a variant in the same gene or because the woman is a carrier of a variant in a gene linked to the X-chromosome (the latter cannot occur with egg donors, since they are previously ruled out).
Recommendations
By using cutting-edge technology and 3 different diagnosis techniques we can fully optimise the genetic test and inform patients of any possible health risks to their future baby. Once we have the results of the genetic test for both parents, the data is cross-matched in order to calculate the couple’s reproductive risk.
If both partners provide gametes and some sort of incompatibility is found, we recommend that Preimplantation Genetic Screening (PGS) is carried out to select the healthiest embryos.
If donor gametes were used, the partner will be matched with a genetically compatible donor.
The genetic disorder test can also be used in the gamete donation programme. By testing the patient and the donor’s gametes (whether sperm or eggs) we can find the «perfect donor».
