Preimplantation Genetic Diagnosis (PGD)

Preimplantation genetic diagnosis (PGD or PGT) is a technique used to detect genetic abnormalities in an embryo created in vitro before implantation in the uterus. Earlier and less invasive than prenatal genetic testing, it offers couples carrying serious genetic disorders a significantly higher chance of having a child free from the targeted condition.

PGD has been available at Erasmus Hospital since 1999 for chromosomal abnormalities and since 2004 for monogenic diseases. Aneuploidy screening, or PGT-A (Preimplantation Genetic Testing for Aneuploidies), may also be offered to couples with a poor reproductive prognosis, as they are at increased risk of embryonic chromosomal abnormalities. This technique provides a complete molecular karyotype of the embryo, allowing the exclusion of abnormal, non-viable embryos and reducing time to pregnancy in this specific patient group.

PGD allows embryo selection based on:

• Chromosomal content, including number and structure (balanced translocations, para- and pericentric inversions, deletions, duplications, or poor reproductive prognosis);
• Absence of abnormal genes, in carriers or patients affected by monogenic disorders such as cystic fibrosis, sickle cell disease, muscular dystrophies, Huntington’s disease, polycystic kidney disease, or mutations predisposing to certain cancers (BRCA1, BRCA2, etc.);
• Embryo sex, in cases of X-linked diseases, with optional direct analysis of the X-chromosome mutation.

Assessment

Each PGD request is reviewed during a multidisciplinary meeting involving gynecologists, geneticists, biologists, and psychologists. If approved and no technical development is required, an IVF-PGD cycle can be scheduled.

For very small chromosomal abnormalities and all monogenic diseases, prior technical development is mandatory. Blood samples from the couple and sometimes close relatives are required. This step is essential to ensure reliable PGD analysis. Development time ranges from 1–3 months for common indications to 9 months or more for complex or rare cases.

In Vitro Fertilization (IVF)

To maximize the chances of transferable embryos, an adequate number of oocytes is required, obtained through controlled ovarian hyperstimulation. Fertilization occurs in the Assisted Reproduction Laboratory using partner or donor sperm, followed by in vitro culture until biopsy.

Biopsy is usually performed on day 5–7 (blastocyst stage). In rare cases requiring FISH, biopsy is done on day 3 (cleavage stage). One cell (cleavage) or 5–10 cells (blastocyst) are removed for genetic analysis.

Cleavage-stage embryos remain in culture for potential fresh transfer on day 5. Blastocyst-stage embryos are cryopreserved while awaiting genetic results (maximum 6 weeks), and transfer is scheduled later.

Genetic analysis techniques

• PCR: DNA amplification for monogenic diseases
• CGH-array (aCGH): full molecular karyotyping
• FISH: fluorescent in situ hybridization for rare small abnormalities
• SNP-array: genome-wide allele polymorphism detection

Embryo transfer

Only genetically unaffected embryos are transferred:

• Fresh transfer on day 5 after cleavage-stage biopsy
• Frozen-thawed transfer after blastocyst biopsy

Appointments and information:
📞 +32 (0)2 555 64 32
📧 DPI [dot] FIV [at] hubruxelles [dot] be
Please bring a complete medical file to your consultation.

PGD can also be used to:

• Detect cancer predisposition mutations
• Detect late-onset disorders (e.g. Alzheimer’s disease)
• Exclude embryos without parental presymptomatic testing
• Select HLA-compatible embryos for stem-cell transplantation

PGD has been successfully applied to hundreds of genetic disorders. Success depends on maternal age, number of oocytes/embryos, disease type, and diagnostic efficiency. Additional IVF cycles may be required in some cases.

The next technological objective is Next-Generation Sequencing (NGS), allowing rapid, direct mutation detection without family studies, particularly useful for multiple genes or de-novo mutations.

PGD success relies on experience and teamwork. Our team has used this technology effectively for 25 years.

Fertility Clinic – MAR (Medically Assisted Reproduction)

• Pr. Anne DELBAERE
• Pr. Fabienne DEVREKER
• Dr. Isabelle DUPOND
• Pr. Oranite GOLDRAT

PGD Coordinator: Mme Chantal Deleau : +32 (0)2 555 64 32, mail : DPI [dot] FIV [at] hubruxelles [dot] be (DPI[dot]FIV[at]hubruxelles[dot]be) 

Technical Coordinator: Mr Eric Gonzalez-Merino

Department of Genetics

Clinical Geneticists:

• Pr. Guillaume SMITS
• Pr. Isabelle VANDERNOOT
• Dr. Sandra COPPENS

Senior Genetics Staff:

• Adeline BUSSON  
• Marie-Laure GRENET  
• Marie BRUNEAU
• Alice LE MORILLON