More accurate detection of chromosomal abnormalities in IVF embryos
5 May 2022
Researchers at the Centre for Medical Genetics at UZ Brussel have developed a new and innovative method, 'Analysis of Parental Contribution for Aneuploidy Detection' or 'APCAD', which allows chromosomal abnormalities to be detected more accurately in very early stage embryos. The technique reduces the risk of miscarriage and improves the success rate of in vitro fertilization (IVF) treatments. The findings of this study were published in the scientific journal Reproductive Biomedicine online.
A new method to detect chromosomal abnormalities in IVF embryos
The novel method, 'Analysis of Parental contribution for aneuploidy detection' or 'APCAD' for short, enables a more complete analysis of the chromosomes, allowing more effective detection of chromosomal abnormalities.
How does it work? Every healthy human being possesses 23 pairs of chromosomes. In each pair, one chromosome originates from the mother and one originates from the father. The new technique verifies the correct balance between the occurrence of maternal and paternal chromosomes. If too much or too little DNA from one parent is found, this indicates a chromosomal abnormality. For example in Down syndrome (Trisomy 21) there are three instead of two chromosomes 21. In that case, twice as much DNA is found from one parent (two copies, usually from the mother) compared to the other parent (one copy) for chromosome 21. This abnormal ratio (67%/33%) is detected with our new method.
Pieter Verdyck, researcher at the Center for Medical Genetics: "Contrary to current methods, APCAD can accurately detect a wider spectrum of chromosomal abnormalities in pre-implantation embryos that are only a few days old. This is valuable for couples trying to fulfill their wish to have a child through assisted reproductive treatment such as IVF. In most cases, chromosomal abnormalities results in a failed implantation of the embryo in the uterus or will result in a non-viable fetus, which will imply a miscarriage and termination of the pregnancy. In a minority of cases, chromosomal abnormalities lead to live births with conditions such as Down syndrome.”
The APCAD test merely requires DNA samples from the prospective parents, not from other family members, which is sometimes the case for other tests. In addition to obtaining information on chromosomal abnormalities, the test is also able to confirm whether an embryo originated from the oocyte and sperm cell of the prospective parents.
Advanced screening for parents with known genetic deficiencies at UZ Brussel
The Centre for Medical Genetics and Brussels IVF, the centre for reproductive medicine at UZ Brussel, already use this advanced technique today for couples who have a known genetic disorder in their family and wish to prevent their children from inheriting the same disorder. Examples of such genetic disorders are hereditary forms of breast cancer, cystic fibrosis or hereditary muscle diseases. Affected prospective parents follow a fertility treatment with pre-implantation genetic testing (PGT). This means that embryos obtained through in vitro fertilization are first genetically tested. Only embryos without the genetic defect are “transferred” back into the uterus. This reduces the risk of miscarriage and increases the success rate of PGT treatment.
PGT procedures currently account for 15% of all IVF cycles in Brussels IVF.
The objective is to use the APCAD method in the future to also help couples with fertility problems who do not have a known genetic disorder in their family. Additional research is required.
UZ Brussel and Vrije Universiteit Brussel (VUB) recently filed a patent application.
This serves as a basis for further research and for possible licensing agreements. Together with other institutions or companies, UZ Brussel and the VUB strive to further optimise this method and make it available to patients on a broader scale.
Karolien De Prez