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
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.
Consultations with specialists prior to start-up
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.
Preparation in the lab
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.
Consultations after completion of lab preparation
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.
Start of your treatment: Assisted fertilisation and genetic screening of the embryos
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.