Preventing hereditary medical conditions?

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Preventing hereditary medical conditions?

Preventing hereditary medical conditions?

If you want to have children but are the carrier of a known genetic abnormality, you can turn to UZ Brussel for treatment with pre-implantation genetic testing, or PGT.

PGT is used to identify genetic defects in embryos created through in vitro fertilisation (IVF) to determine whether they carry the inherited condition. The embryo is only ‘returned’ to the uterus after genetic testing for a healthy pregnancy.

The PGT pathway is made possible thanks to close cooperation between Brussels IVF and the Centre for Medical Genetics (CMG) at UZ Brussel. Genetic analysis is conducted during an IVF cycle involving ICSI (Intracytoplasmic Sperm Injection). Within this pathway, you are monitored by a fertility doctor and a doctor-geneticist, along with specialised midwives who coordinate your PGT pathway.

Good to know

Why do you always have to do ICSI with PGT?
Fertilisation must take place in the lab for genetic testing of an embryo. We always perform ICSI in this instance.

In IVF, sperm cells are added to the oocytes in a Petri dish in the lab, leaving the sperm to find the oocytes themselves. In ICSI, one single sperm is injected into each oocyte. That way, we do not risk testing genetic material from another sperm (instead of the embryo), which might be the case with IVF.

For whom?

PGT is mainly performed on people with an increased risk of having a child with an inherited condition or those who struggle to conceive due to a genetic disorder. In principle, we can detect any genetic condition at embryo level, provided we have all the necessary information about the condition and its cause beforehand, so that we know which genetic disorder to detect. It may be a chromosomal abnormality or an abnormality at the level of one or more specific gene(s). Moreover, it must be established that the condition is caused by the change in the hereditary material. In principle, changes in the hereditary material whose significance is unknown or insufficiently known do not qualify for PGT.

From application to treatment: a roadmap

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Contact us

Send an e-mail to cmg@uzbrussel.be. Specify the genetic condition that may have an impact on your desire to have a baby.

The first step of PGT treatment is to complete your file to ensure we understand which condition needs to be detected. We therefore need all available information about the condition and its cause prior to the consultation.

To this end, you should provide us with lab results of previous genetic testing (unfortunately a consultation report is not sufficient) and any other medical reports you may have, together with the completed questionnaires and the administrative document so that your file can be reviewed. If you are eligible for PGT treatment and your file is complete, we will schedule an initial appointment with a genetic expert (geneticist), a PGT coordinator, and a fertility specialist for you.

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Consultations with specialists prior to start-up

Your first consultation is with the clinical geneticist (genetic expert) and the PGT coordinator. They will discuss all the options in your specific situation with you.
Your fertility will be assessed during the consultation with the fertility specialist (gynaecologist). It is perfectly possible that there are no fertility problems in a PGT pathway. However, we always use IVF with the ICSI technique for testing embryos.

In most cases, additional preliminary examinations and tests are also scheduled to complete your medical records.

A karyotype or chromosome map will be created for each prospective parent by default (unless this was already done elsewhere and these results are available). This test shows that the prospective parent was born with the usual number of chromosomes (46) and that there are no changes in the shape of these chromosomes. Karyotyping is performed for everyone because changes in chromosomes have a direct impact on the chances of success of a PGT pathway.

In addition, we also screen prospective parents for a number of less rare hereditary conditions, even if there is no personal or family history of these conditions. We check for the most common types of genetic mutations, such as cystic fibrosis (CFTR gene), Fragile X Syndrome (FMR1 gene) and for spinal muscular atrophy (SMN1 gene). Initially, we test one of the two prospective parents. Depending on the outcomes, we may decide to test the other parent. In the event that you use donor sperm or donor oocytes, the oocyte or sperm donors have also been screened for these conditions.

These genetic tests are reimbursed (except for the copayment) by Belgian mutual health insurance funds. You can also opt for expanded carrier screening (BeGECS) in which we screen both prospective parents for the genes of 1,000 autosomal recessive disorders and 100 X-linked diseases. BeGECS is not reimbursed by Belgian mutual health insurance funds. You will be informed of the exact price of this screening during your consultation.

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Preparation in the lab

Depending on whether or not specific PGT testing needs to be developed, the waiting time may be shorter or longer.
If no specific PGT needs to be developed, preparations in the lab are completed in a matter of weeks.
If (PCR or SNP) PGT needs to be developed, this can be done after your consultation and as soon as the Medical Genetics lab has all the necessary lab reports and (family) samples. PGT testing establishes an efficient and reliable genetic diagnosis based on one or more cells of an embryo.
The test development phase takes at least four months.

In principle, PGT development is reimbursed once only by Belgian mutual health insurance funds. If you have already undergone PGT in another centre, it is vital that you inform us of this so we can check your eligibility for reimbursement of a new round of PGT development.

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Consultations after completion of lab preparation

Once the lab preparations have been completed, you visit us for another consultation.

The clinical geneticist and fertility specialist discuss the results with you and prescribe your fertility treatment. That same day, the fertility counsellor will review all the steps of the treatment with you and schedule a start date. The counsellor will explain which medication you must take, the cost of your treatment, oocyte retrieval, embryo transfer... as well as the legal and financial implications.

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Start of your treatment: Assisted fertilisation and genetic screening of the embryos

In in vitro fertilisation, fertilisation of the oocyte by the sperm cell does not take place in the fallopian tube, but outside the woman's body, in a petri dish in the laboratory (‘in vitro’ means in glass).

In PGT, we always use ICSI as the fertilisation technique, meaning we inject one sperm into each oocyte a few hours after oocyte retrieval. That way, we do not risk testing genetic material from another sperm (instead of the embryo), which might be the case with IVF. After injection, the petri dish goes into an incubator that mimics the conditions in the uterus as closely as possible. Depending on the PGT, the biopsy is done on day 3 (PCR) or on day 5/6 after fertilisation (SNP or NGS). After biopsy on day 3, the embryo develops further in the incubator until day 5 or 6, after which it can potentially be used for ‘fresh’ or ‘frozen’ transfer. After biopsy on day 5/6, no ‘fresh’ transfer is possible and all embryos are frozen. In that case, genetic screening takes 4 weeks from the time of biopsy. As soon as the test results are available, a transfer of frozen embryos can be scheduled.

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Welke medisch begeleide vruchtbaarheidsbehandelingen zijn er?

IVF and ICSI

Assisted fertilisation in the lab

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Stimulation

Assisted reproductive technologies usually involve some form of ovarian stimulation

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Cryopreservation

Cryopreservation of gametes, embryos, or tissue

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Embryo testing

Embryos obtained after fertilisation in the lab are first examined for the hereditary genetic disorder, before being transferred into the womb

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Did you know?

PGT is possible in almost all cases even if we do not have (all) the family samples at our disposal, but this may affect the duration of test development.

Once we start developing the PGT, we ask couples to only have protected sex and stop trying to conceive spontaneously. PGT is individually developed and expensive. You will be charged for this as soon as you start treatment. Moreover, in a spontaneous pregnancy, you have no prior genetic screening of your baby and so the hereditary condition may be passed on unintentionally.

PGT is a highly reliable screening technique, with a minimal risk of misdiagnosis. You can also elect to have an invasive prenatal test (chorionic villus sampling or amniocentesis) during your pregnancy to diagnose and confirm genetic disorders. In addition, the medical genetics department at UZ Brussel offers you the opportunity (in most cases) to have diagnostic tests performed after your baby's birth.

For PGT test development, the lab must be provided with the original lab reports, which describe the mutation at molecular level. A genetic consultation report is not sufficient.

We recommend every pregnant woman, even after treatment with PGT, to undergo genome-wide non-invasive prenatal testing (NIPT) that checks all chromosomes. Belgian patients are asked to have their NIPT done at UZ Brussel if at all possible.

Five common questions about having children when you have an inherited condition answered:

How long does test development take?

Each disease requires a specific and individual test. During your consultation with the geneticist, you will be given an estimate of the time needed to develop your personalised PGT (usually several months). To develop the test, we need blood samples from both prospective parents. In addition, we often do blood or DNA tests on family members for monogenic disorders. We try to understand how the error in the DNA code is inherited and where exactly in the embryo's DNA to look for the genetic error. The duration of PGT treatment may vary depending on what is required for your situation. The indication determines whether this takes a few weeks or at least four months.

Can PGT that was developed by another centre also be used?

PGT is lab-specific. This means that PGT developed at another centre cannot be used by our lab at UZ Brussel. Previously developed PGT does not affect the duration of test development in other words.

How safe is PGT?

In PGT, we gently remove one or more cells from the embryo’s outer shell in the lab. After the biopsy, the embryo generally remains intact and continues to develop normally. Postnatal follow-up of babies born at UZ Brussel after PGT treatment shows that they are just as healthy as babies born after a ‘conventional’ IVF or ICSI procedure (without PGT). Babies born after IVF/ICSI and PGT were monitored by the Centre for Medical Genetics (CMG). Some were also seen at age two. They are just as healthy and their development is similar, in comparison with just as many ICSI babies and babies born after natural conception. Data from the PGT Consortium of the European Society of Human Reproduction and Embryology (ESHRE) confirm that the health of newborn PGT children is comparable to that of ICSI and IVF children. Performing an embryo biopsy does not appear to increase the risk of malformations. However, further follow-up studies remain necessary, especially in the long term. All couples who become pregnant through PGT treatment are therefore asked to participate in the CMG's follow-up programme with their baby/ies.

Why do we need blood or DNA samples from (first-degree) relatives?

Often, the genetic abnormality occurs in several family members (familial variant). In the case of a familial variant, the lab determines during test development how the causal variant is inherited between family members. This requires blood or DNA samples from (first-degree) relatives of the prospective parent with the genetic abnormality. This information is used for an accurate diagnosis of the embryos.

Can I choose the sex of my baby?

Sex selection of embryos is only legal in Belgium for medical reasons, such as sex-linked diseases (passed on through the X or Y chromosome). In the case of X- or Y-linked diseases, only female or only male embryos are eligible for transfer. However, in most sex-linked diseases, we are able to specifically determine the causal variant and transfer healthy male and female embryos back into the womb. The personal preferences of prospective parents can never be a reason for sex testing of embryos.

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