Genetic matching is a genetic compatibility test that is performed before conception and allows a couple to know, through a detailed genetic study, the possible mutations and alterations of their genes that are likely to be transmitted to a common offspring. This genetic test can be carried out whether one’s own gametes are to be used, or when donor eggs and/or sperm are needed.
The importance of genetic compatibility
According to the World Health Organization (WHO) about 1% of children in the world are born with some kind of genetic alteration. The reason for this is that most people carry, almost always unknowingly, between three and five recessive genetic mutations. Some are rare but others, such as cystic fibrosis or spinal muscular atrophy, are relatively common (the mutation is present in 1 in 25 people and 1 in 50, respectively). These inherited genetic abnormalities also include those linked to the X chromosome.
Being a carrier of a recessive genetic alteration does not imply that you suffer from the disease, nor that no family member has suffered from it before, nor that it will be passed on to offspring. In fact, many of these mutations lie dormant in a family for generations without ever manifesting themselves. However, if it so happens that both members of the couple have the same gene altered, there is a very high risk (25%) that their children will suffer from one of these diseases, some of them with a serious prognosis.
On the other hand, in assisted reproduction processes, the aim is not only to improve gestation rates or reduce the risk of multiple pregnancies, but also to ensure that the children are born healthy. And, although the vast majority of genetic diseases cannot be cured, their appearance and risks can be minimized by carrying out a prior genetic study of the parents. In this sense, genetic compatibility testing is the key tool to achieve this, since genetic testing is the only way to detect these types of mutations.
How is the genetic compatibility test performed and what information can it provide?
Performing a genetic compatibility test is a simple procedure, it is enough to perform a blood test on both parents. Afterwards, both samples are studied and analyzed to detect possible anomalies in each of the members of the couple and in common. Preconception genetic tests can study a variable number of diseases. At CREA we use the Gene Profile panel, designed by Sistemas Genómicos, which studies 32,749 mutations in 320 genes of 345 hereditary diseases, 318 autosomal recessive and 27 X-linked.
The choice of these diseases to be detected has been made according to the following criteria established by the WHO:
- Prevalence in the general population.
- Incidence in pediatric emergency cases.
- Diseases that most frequently cause neonatal death.
- Diseases most frequently causing intrauterine death.
- Diseases included in the extended neonatal studies.
In which cases is genetic testing recommended?
- In any couple who wish to know the genetic risk of transmitting diseases to their offspring.
- In people with a history of genetic alterations in their family.
- In couples who have had a child with some type of disease derived from a recessive genetic mutation (hereditary) or not. There are couples who undergo this compatibility test after having had a sick child naturally, avoiding running that risk in a second pregnancy.
- In couples who require gamete donors (eggs or sperm).
What happens if the genetic compatibility test reveals any anomaly?
Once the data from the genetic compatibility test have been obtained, the medical team will advise the couple on whether to attempt a natural pregnancy or to initiate a process of in vitro fertilization (IVF) to study their embryos in the laboratory and transfer to the uterus one that has not inherited the disease (preimplantation genetic diagnosis). If the genetic compatibility of the couple is unfeasible, there is the option of using donor gametes. In this case, the genetic test would be performed on the member of the couple that provides their gametes and the selected donor to ensure the genetic compatibility of both. This genetic matching is called “Genetic Matching”. At CREA the panel we use is one of the most advanced and detailed on the market, and not only examines mutations in the coding DNA (exons), but also other mutations described in the other parts of the gene such as regulatory regions, introns, exon-intron intermediate zones and flanking regions. This ensures maximum detection capability.