Carrier test - revealing hidden genetic defects in DNA

Carrier test is a preconception genetic test aimed at revealing hidden (recessive) mutations in DNA, which are the cause of serious hereditary genetic diseases.

Everyone is an unwitting carrier of various genetic mutations. If both partners carry the same mutation, there is a significant risk that the offspring will develop the full-blown disease.

Serious genetic diseases with a high frequency of carriers in the European population include, for example, cystic fibrosis, spinal muscular atrophy or fragile X syndrome.

In vitro fertilization (IVF) techniques are not required to perform the test.

Carrier screening tests are genetic tests that the scientific community is increasingly recommending in connection with informed family planning. It is primarily used to identify individuals at risk that their offspring will be carriers of a  serious hereditary genetic disease.

Healthy carriers of genetic diseases are almost always asymptomatic (without any symptoms of the disease) and without a family history that would suggest the presence of the disease.

Pathologies included in carrier screening are medically significant single-gene disorders with autosomal recessive or sex-linked inheritance.

Carrier tests are intended for patients who:

Have a genetic disease in the family;

Are in consanguineous marriage;

Are planning a family and would like to know if they are carriers of some serious genetic diseases;

Want to know for the future if they are carriers of certain mutations included in the panel of tested genes.

Statistics and disease probability:

Today, about 8,000 single-gene inherited diseases are known, which include both recessive and dominant variants. 

  • The risk of a recessive disease in offspring is 25% in partners of carriers. 
  • With a dominant genetic disease, the risk is 50%, but in this case the offspring inherits the disease either from an affected parent, or the disease appears “de novo” based on an acquired mutation in the DNA of reproductive cells (eggs or sperm).

Population studies show that the incidence of serious single-gene diseases is 0.36% per 1 million live births.

Between 0.8% and 1% of European couples are at risk of having a child with a serious genetic autosomal recessive disease.

About 6% of children are born with a serious birth defect of genetic or partially genetic origin.

Inheritance of an autosomal recessive disease when both partners are carriers:

Principle of genetic testing:

3 ml of blood is sufficient for the test. Make an appointment for blood sampling at the reception of the ReproGenesis clinic.

Carrier tests Genescreen® from Genoma are performed using highly advanced next-generation sequencing (NGS), a technology that examines the nuclear and mitochondrial genome with extensive coverage of medically relevant genes.

Genescreen® performs whole-exon sequencing (that is, it analyses the DNA structure of all parts of the gene that are involved in protein production) to identify all mutations of the gene that is included in the test panel.

Genescreen® offers four types of test panels, according to the number of genes examined:

  • Focus panel: 30 genes (30+ genetic predispositions)
    Screening of the most common recessive and X-linked genetic disorders in the European population, such as cystic fibrosis, sickle cell disease, beta-thalassemia and hereditary deafness.
  • Easy panel: more than 300 genes (600+ genetic predispositions)
    Screening of a targeted number of genes to identify the most common and clinically significant inherited genetic diseases.
  • Standard panel: more than 550 genes (700+ genetic predispositions)
    Includes the most common and clinically relevant diseases, including disorders specific to individuals of Ashkenazi Jewish descent.
  • Expanded panel: more than 1000 genes (1400+ genetic predispositions)
    Screening for a wide range of genes and genetic disorders in general populations, recommended by ACMG (American Collage Medical Genetics and Genomics) and ACOG (American College of Obstetricians and Gynecologists), including specific genetic disorders.

Next procedure in case of hidden (recessive) detection of mutation in DNA

If there’s a mutation found in one of more examined genes within the Carrier testing, i tis advised to examine for these mutations also the partner with whom you plan to start family.

In case that the Carrier test shows the mutation on the same gene in partner’s results, i tis recommended to the couple to undergo an IVF treatment with genetic testing of embryos (PGT-M) et to choose for the transfer only the embryo that didn’t inherit the mutation on the examined gene after his parents.

If the genetic testing (PGT-M) proves the mutation in the embryo, inherited only from one of the parents, it is possible to transfer it, but i tis necessary to keep in mind the fact that the baby will be a carrier of stated monogenic disease and in his adulthood, he will deal with the same situation as his parents.


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