Genetic testing when planning a pregnancy

We're Both Healthy. Why Do We Need Genetic Testing?Most genes are present in two copies: one inherited from the mother and the other from the father. For many inherited conditions, a change in one copy of a gene does not cause symptoms because the other copy continues to function normally. A person may therefore be healthy and unaware that they are a carrier.

If a child inherits variants from both parents in the same gene that disrupt its function, the child may develop a genetic disorder. Therefore, having no symptoms and no known family history of a genetic condition does not eliminate the risk. This is precisely what carrier screening helps identify. 1

DNA double helix. 3D visualization: Braňo / Unsplash

Can the Risk of SMA Be Identified Before Pregnancy?You may have seen fundraising campaigns for children with spinal muscular atrophy (SMA). This condition affects the nerve cells that control muscles and can make movement, swallowing, and breathing difficult.

Carrier status for the most common form of SMA can be identified in prospective parents even before conception. Carriers themselves are usually healthy.

If both partners are carriers, the probabilities for each pregnancy are:

25% — the child will have SMA;
50% — the child will be a healthy carrier;
25% — the child will inherit neither of these genetic variants.

These probabilities remain the same for every new pregnancy.

Knowing about an increased risk gives prospective parents time to discuss their family planning options.

The test does not detect every case of SMA carrier status, so a negative result must be interpreted with its limitations in mind. 2

Who Should Consider Carrier Screening, and When?Any couple planning a pregnancy can discuss carrier screening with their healthcare provider.

Ideally, screening should be performed before conception. This allows time for partner testing, genetic counseling, and informed decision-making.

If you are already pregnant, carrier screening is still possible. Whether to undergo testing is entirely your choice.

If there is a history of an inherited condition in your family, be sure to tell your doctor. In such cases, targeted genetic testing may be needed instead of a standard screening panel. 3

What Is Adventia, and Which Conditions Does It Screen For?Adventia is one of the carrier screening tests offered by Medicover Genetics.

A "panel" refers to a set of genes included in a genetic test. Adventia is available in both basic and expanded versions. 4

The Core panel includes 22 genes. It screens for carrier status associated with spinal muscular atrophy (SMA), cystic fibrosis, phenylketonuria, thalassemias, certain inherited forms of hearing loss, and other conditions. It also includes testing related to fragile X syndrome.

The Comprehensive panel includes 231 genes. In addition to the conditions covered by the Core panel, it screens for further inherited disorders, such as Wilson disease, Pompe disease, and familial Mediterranean fever. 5

During a consultation, I can help you understand which level of testing is appropriate for your family.

The largest panel does not always provide the answer to a specific question. Family history and the capabilities of the test itself are important considerations.

Do Both Partners Need Genetic Testing?Both partners can be tested at the same time, or testing can begin with just one partner.

If carrier status is identified, the doctor will determine which tests are needed for the other partner.

During pregnancy, testing both partners simultaneously allows for a faster assessment of potential risks. 3

For certain X-linked conditions, a risk may exist when the woman is a carrier, regardless of the male partner's test results.

Therefore, a couple's results should not be interpreted solely on the basis of whether both partners carry variants in the same gene. 6

What Should You Do If Carrier Status Is Detected?A positive carrier screening result in one person does not automatically mean that their child will have a genetic disorder.

The specific genetic finding, the pattern of inheritance, and, when necessary, the partner's test results must all be evaluated.

If an increased risk is identified, the following options can be discussed during a genetic counseling consultation:

Natural conception followed by prenatal diagnostic testing for the specific condition during pregnancy;
In vitro fertilization (IVF) with preimplantation genetic testing for monogenic disorders (PGT-M), allowing embryos to be tested for the condition before transfer;
The use of donor eggs or sperm, taking the identified genetic risk into account.

The decision belongs to the prospective parents. The doctor's role is to explain the possibilities and limitations of each option. 6

If the Result Is Negative, Is Further Testing Unnecessary?A negative result reduces the risk of the conditions included in the screening, but it does not eliminate that risk completely.

The test examines specific genes and cannot detect every possible genetic change. It cannot guarantee that a child will be born free of disease. 6

Carrier screening does not replace ultrasound examinations, non-invasive prenatal testing (NIPT), or other tests performed during pregnancy.

These investigations serve different purposes. For example, standard NIPT assesses the risk of certain chromosomal abnormalities in the fetus. 7

How Is the Test Performed, and Who Explains the Results?Adventia requires a swab taken from the inside of the cheek, known as a buccal swab.

DNA is extracted from the collected cells and analyzed in a laboratory. 4

You can start with a consultation with a gynecologist who is familiar with carrier screening.

If an increased risk to the child is identified or the test reveals complex genetic findings, consultation with a medical geneticist will be necessary.

Sometimes, the results may also have implications for the health of the person being tested. This is another important topic to discuss with your doctor. 8

Carrier screening helps identify certain inherited risks even before pregnancy.

If an increased risk is found, prospective parents will have time to discuss the results with a genetic specialist and decide how to proceed with their pregnancy plans.