There have been some amazing developments in the area of IVF across the world over the last few years, particularly in the area of genetic testing. Understandably, most parents hope for a chromosomal normal baby, and the great news is that there are a range of treatments that can assist that involve a sophisticated scientific technique called preimplantation genetic testing (PGT).
PGT allows for the assessment of cells from a very early pregnancy following the creation of embryos using IVF. It analyses their genetic structure before they are implanted and tests embryos for chromosome variation or single gene conditions. It is done when the embryo is five days old (what is called the blastocyst stage) and some cells are biopsied from the outer cell mass, where the membranes and placenta derive from. Only chromosomally healthy embryos or those unaffected by a specific disorder are selected for transfer which maximises the chance of a healthy baby. The process is typically undertaken in one of two ways — PGT with next generation sequencing and PGT with karyomapping.
PGT with next generation sequencing
Next generation sequencing in IVF is a pre-implantation genetic testing technique that is able to amplify the DNA from the cell’s nucleus by multiplying it many thousands of times. Sequencing technology is then used to count the number of copies of each chromosome present in the cells from the embryo. Yes, it sounds complicated! But in simple terms, it allows for the determination of the chromosomal structure of a baby.
The process involves testing all 24 chromosomes in an embryo to enable the selection and then transfer of only those embryos that have a chromosomally healthy profile. This increases the change of a successful pregnancy.
PGT with karyomapping
Similar genetic testing techniques involve what is known as karyomapping in IVF which may be used for individual genes or for rearrangements of chromosomes. This technology is not widely used in Australia, but common in the United States. It is a highly sophisticated scientific technique that involves the pre-implantation genetic testing of embryos to look for the presence of a single gene disorder.
This allows embryos that are not affected by a specific disorder to be selected for embryo transfer during an IVF cycle, which prevents the condition being passed on to any future children. The length of time taken for the assessment phase will depend on how much genetic information is already available from the patient.
DNA samples are collected — usually via a simple saliva or blood test from the couple as well as other family members. Preliminary testing of these samples allows a unique DNA fingerprint of the faulty gene to be determined. Analysis typically takes two to four weeks to establish whether Karyomapping is appropriate for the individual.
If so, embryos are created as part of an IVF cycle and a few cells are removed from each embryo for analysis. If there is an unaffected embryo available for transfer, this will be transferred back into the female’s uterus with a chance that it will produce a successful pregnancy and a healthy baby.
At Queensland Fertility Group, we offer preimplantation genetic testing for chromosome abnormalities and single gene defects. Genetic testing is an area of science where much change has occurred and continues to develop. Please contact me if you would like to discuss these scientific techniques further as part of your IVF journey. Call (07) 3353 3100 to book an appointment today.