A rare disease is considered to be those diseases that affect a small number of people within the population and that have specific characteristics. Many of these are genetically transmitted, which makes some parents wonder if they can be prevented. Inside of Assisted reproduction, there are two methods that could help prevent transmission of rare inherited diseases.
February 29 is World Rare Disease Day. It is, as Eurordis says in the report 'Rare diseases: awareness of this priority for public health', an important day to give visibility to all those who suffer from this type of disease, as well as to recognize the progress that has been made and continue fighting for research and social solidarity.
In Spain, the World Health Organization (WHO) estimates that there are more than 3 million people with rare diseases. Likewise, 80% of these diseases are of genetic origin, which is why assisted reproduction can play a fundamental role in preventing these types of problems.
Despite the fact that most of this type of disease has no cure, from the genetic point of view, specifically, through assisted reproduction, hereditary anomalies can be diagnosed and prevented. With this, it is possible to eliminate the concern that parents have that their child is born healthy and without inheriting any disease.
There are different methods such as Genetic Compatibility Test (TCG) or the Preimplantation Genetic Diagnosis (PGD) that detect the risk of suffering disorders, both in the parents and in the embryo. This makes it possible to avoid the transmission of diseases and, consequently, the number of healthy children is greater. The chances of the child being born healthy are reduced to 25% when both members of the couple are carriers of the same disease.
Of the 7,000 genetic diseases that are currently known, the most common that are tried to avoid through these techniques are:
- Cystic fibrosis. Due to a defective gene, a fluid is produced that affects certain organs of the body and that causes the inability to grow and gain weight.
- Fragile-X syndrome. It is related to the X chromosome. It causes moderate to severe mental retardation.
- Hemoglobinopathies. It is a defect in DNA that affects blood clotting.
- Muscular dystrophy. It produces the progressive wear of the muscles.
- Neurosensory deafness. It is a type of hearing loss. It occurs from damage to the inner ear, the brain, or the nerve that runs from the ear to the brain (auditory nerve).
People known as asymptomatic are those who, despite being healthy and having no symptoms, have a hereditary disease. The fact that it is not suffered as such does not mean that there is no risk of transmitting it when having a child. Therefore, the Genetic Compatibility Test It is very useful to know the genetic characteristics of each person before having offspring and thus know the possibilities of transmitting a disease.
This method consists of performing a genetic test for the detection of rare disease carrier status in both members of the couple in order to determine the altered genes that the members of the couple have and thus observe the chances that their child would have of suffering from a disease inherited. There will be a genetic risk when the two members of the couple coincide in being carriers of the same rare, which only happens in 2-3% of cases.
It is possible at this time to have the GCT done before pregnancy. If it is by natural means, it will be important to know if there is a risk of carrying a genetic disease. In the event that it is through assisted reproduction through a donor, it serves to have the possibility of choosing one who does not have the same disease as the other member of the couple.
In the case of discovering through the Test that you are a carrier of a disease, there will be no problem, except that the same gene is manifested in both parts of the couple. In that case, as the chances of the offspring suffering from a disease would be high, it would be recommended to proceed with In Vitro Fertilization (IVF) and carry out the Preimplantation Genetic Diagnosis. Another option would be to go for gamete donation.
PGD is performed in In Vitro Reproduction techniques. This method genetically studies the embryos generated before their transfer to the uterus. Through this, it is about locating those that present abnormalities, which can cause diseases and selecting the one that is healthy. The use of this technique allows the transmission of diseases between generations to be minimized.
Preimplantation Genetic Diagnosis must be carried out when at least one of the members of the couple suffers from a dominant hereditary disease that can transfer to the baby. Also, women of older ages or who have suffered unprovoked abortions are advised.
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