Pre-implantation genetic diagnosis is an advanced examination for older couples who would like to become parents or when in vitro fertilisation is particularly difficult. In Switzerland, the treatment is successfully practised by specialists of the Hirslanden Private Hospital Group.
Diagnostic methods: PGT-A, PGT-M and PGT-SR
Nowadays, the genetic material of embryos can be specifically examined to determine their genetic condition before transfer. PGT-M (pre-implantation genetic testing for monogenic disease) is used as a method of PID (pre-implantation diagnosis) for couples with hereditary diseases such as cystic fibrosis. PGT-SR is used if there are structural defects in the chromosomes. A PGT-A test is indicated when all embryos have to be examined for age-related chromosome deviations, for example.
Suitable patients for PGT-M
Known mutations which are proven to cause diseases with serious health effects that will probably manifest before the age of 50 and for which there are no effective and appropriate treatments.
Suitable patients for PGT-SR
- Sterility
- Increased abortion risk/status post- abortion(s)
- Abnormalities
In general, PGT-SR is only recommended if the technique used is able to record all expected unbalanced forms of translocation (inversion, reciprocal translocation, Robertsonian translocation).
Suitable patients for PGT-A
- Women older than 38
- After miscarriages
- After several unsuccessful embryo transfers
- If the partner’s semen parameters are inadequate
- When couples want to ensure that no embryos with the wrong number of chromosomes are used
PGT procedure
On the fifth or sixth day, the embryo has developed into a blastocyte. During the embryo biopsy, the biologist removes only five to ten of a total of a few hundred cells.
The tiny tissue samples are labelled very carefully and transported by courier to the specialist genetic laboratory Genetica AG in the heart of the city of Zurich. It takes a few weeks until the results are available.
PGT-A recognises embryos which are not capable of surviving or would result in miscarriages in 98% of cases.
Successful method
Unlike the other methods, during pre-implantation genetic diagnosis with aneuploidy screening (PGT-A) the embryo is not transferred immediately. Four weeks after the egg cell has been harvested – when all data is available and no genotype discrepancies have been determined – the specialists of Hirslanden Hospital use the embryo. The success rate of embryo transfers after PGT-A is around 60% – and the woman’s age has no bearing on this.
Find out more about the success rates and risks of in vitro or ICSI treatment in the overview of the topic “Artificial Insemination – Fertility Treatment in Switzerland”.