What are recessive genetic diseases?

Approximately 1 in 100 (or 10 in 1000) people suffer from a genetic disease. Seven of these 10 suffer from dominant genetic diseases and the other 3 from genetic recessive diseases.

Recessive diseases appear when two mutated copies (or alleles) of the same gene are inherited. For this to be possible, it is necessary that both the father and the mother are carriers of the disease, that is, that both have an altered copy of the gene and that, by chance, the two have passed the altered copy to their offspring. A carrier of a genetic mutation causing a recessive disease does not manifest the symptoms of the disease and, in fact, all people are carriers of mutations in genes that cause recessive genetic diseases, without this entailing any clinical manifestation. When both partners are carriers of recessive mutations in the same gene, there is a 25% chance that their children are affected by the disease, 50% are unaffected carriers, and 25% are free of mutation (non-carriers).

In the case of recessive diseases linked to the X chromosome, the gene causing the disease is located in this sexual chromosome. Half of the children of a carrier mother will receive the mutated copy of the gene. The effects of this mutated copy will be different if a child is conceived. Male descendants who receive the mutated copy of the gene will be sick; whereas girls with only one mutated copy do not tend to present clinical manifestations, and will be carriers (although due to the phenomenon called inactivation of the X chromosome, the presence of symptoms can not be totally ruled out).

What is the purpose of a carrier test?

From the knowledge of the carrier status of a series of diseases in both members of a couple, it is possible to know precisely the risk of transmitting these genetic diseases to the offspring.

This information, well communicated and used, translates into greater reproductive autonomy for the couple and the possibility of making better informed decisions.

What does our qCarrier Plus offer?

QCarrier® Plus can detect more than 9,000 known mutations in more than 300 genes that cause recessive diseases, which can be classified into four groups:

  1. Serious illnesses with very serious repercussions for health and that usually have a negative impact on people’s life expectancy and quality of life.
  2. Diseases of variable severity, with a variable spectrum from moderate to subclinical conditions, which in general can affect the quality of life, but do not affect in a decisive way the life expectancy of people.
  3. Very rare diseases, with serious repercussions for health but with a high incidence in certain populations of the world, especially in populations of Jewish, Nordic and certain Mediterranean areas.
  4. Diseases linked to the X chromosome, including diseases that, due to their characteristics, could be included in any of the three previous groups, but which present this particular inheritance pattern.
What results can I expect from the qCarrier Plus test?

With the performance of this test it is possible to identify known genetic variants in any of the analyzed genes, determining their carrier or non-carrier status, which will allow to know the probability of transmitting this variant to the offspring of the analyzed person.

Although thousands of population variants (called polymorphisms) and more than 9,000 known mutations have been described among the analyzed regions, the finding of other variants for which there is no population information and, therefore, not known if they are related to any disease cannot be ruled out (variants of uncertain significance).

There is also the possibility of finding genetic variants of uncertain significance even though they have been reported in the literature, for which there is incomplete or contradictory evidence about their pathogenicity. In these cases it will only be possible to discuss the existing evidence without the possibility of making medical decisions in this regard. You must decide whether or not you want to be informed in case of detecting genetic variants of uncertain significance, even knowing that as of today it will not be possible to modify the guidelines of clinical action.

Also, there is the possibility that mutations are identified that allow to determine that one is afflicted with a recessive disease, although there are still no clinical manifestations of it. An example of this could be the identification of mutations in a gene that is the cause of a disease with variable expressivity or late onset that until now has not been diagnosed since specific symptoms have not yet appeared. The identification of a recessive genetic disease, so far undiagnosed, can have important repercussions for both you and your family. You must decide whether or not you want to be informed in the case of fortuitous findings that have a proven clinical impact. In any case, the clinical data from the test will be provided to the geneticist in order to continue his assistance. This will be done respecting the patient’s confidentiality and following the guidelines set forth in the Organic Law on Data Protection and the Biomedical Research Law.

Data obtained today can be reinterpreted in the future

Knowledge of the function of genes and their relation to diseases has increased dramatically in recent years and continues to increase at a very high rate; but we are still far from the complete understanding of the meaning of the entire DNA sequence that makes up the human genome and its variations.

Thus, it is possible that the study detects some genetic variant not previously described in other people to date, and that should be considered as a VOUS (variants of uncertain significance).
This means that a genetic alteration that is identified and that, to this day, is classified as having unknown repercussion, can be reclassified in the future as a cause of disease when the knowledge advances.

In the event that this happens you may be recontacted by your doctor.

What do we need to perform a qCarrier Plus test?

It will be necessary to obtain a biological sample (1 tube of blood of 5-8mL, a drop of blood in a special paper, or a little saliva) from which the DNA will be extracted for theperformance of the test.

The remaining DNA will be preserved for future validation studies. Even if we keep it, you will always need to give your written consent to do any other type of analysis with your sample.

You have the right to decline this consent at any time, without giving any kind of explanation and without having any repercussion on the quality of the treatment you need to receive.

Use of sequencing results for research purposes

qGenomics is a company committed to the advance of knowledge and collaborates in research projects regarding the genetic basis of rare diseases with researchers of recognized national and international prestige.
The information that will be obtained from the study of your DNA is very important for the advance of knowledge about genetic diseases, and can help many other people. If you do not state otherwise, the results of your analysis will be kept completely anonymous and only your doctor will have the key to undo anonymity.

In this way, the data obtained can be shared only in an aggregated and anonymous way with other accredited researchers. If, as a result of these investigations, there is any relevant discovery for a genetic condition that may affect you, your doctor will be informed and it will be he/she who contacts you to transmit this information.

I have more questions about carrier tests. Who can I contact?

Your doctor can inform you about all the details of this test.

However, for any additional questions you may have, you can contact us through our telephone assistance department (932 301 270)

or by email to info@qgenomics.com