You are here: Home  Treatment options  Genetic testing of the embryo

GENETIC TESTING OF EMBRYOS


The genetic testing of embryos before they are returned to the uterus has been permitted in Austria since 2015. A distinction is made between:

  • PGT-A (Preimplantation Genetic Testing for Aneuploidy) for the investigation of maldistributions of chromosomes in the embryo and
  • PGT-M (Preimplantation Genetic Testing for Monogenic Defects) to investigate the function of single-cell genes (hereditary diseases)

The following criteria must be met in order for PGT-A to be carried out in Austria:

  • The couple who wish to have children have already carried out at least three unsuccessful IVF attempts and a chromosomal cause has been assumed.
  • Or if a woman has had at least three miscarriages or stillbirths, the cause of which was most likely in the child’s chromosomal makeup.

PGT-M is permitted if, due to a genetic modification in at least one parent, there is a serious risk of miscarriage, stillbirth or a hereditary disease of the child.

A hereditary disease is present if the child becomes so ill during pregnancy or after birth that they can only be kept alive through the constant use of modern medical technology or the constant use of other medical or nursing aids that severely impair the quality of life, severe brain damage or will suffer from severe pain that cannot be effectively treated.

PGT-M is only approved for certain hereditary diseases in Austria. The list of diseases is growing every year, but it is far from complete. In order to obtain permission to examine a ‘new’ hereditary disease using PGT-M, an application for approval must be submitted to the Wissenschaftlichen Ausschuss für Genanalyse und Gentherapie (Scientific Committee for Gene Analysis and Gene Therapy) (WAGG). After the WAGG has assessed the application, a disease is ‘released’ and from then on embryos can be examined for this disease using PGT-M.

 

One of the diseases for which PGT-M is approved is cystic fibrosis. Cystic fibrosis is the most common autosomal recessive inherited metabolic disease in Europe, affecting four in one thousand people. The reason is that both maternal and paternal copies of the responsible CFTR gene on chromosome 7 of the child are not functional.

Every 25th person in Austria is a carrier of the CFTR mutation, but despite being healthy they can pass the mutation on to offspring. If two CFTR carriers decide to have a child, the offspring can develop full cystic fibrosis.

There are a large number of CFTR mutations leading to disorders on several levels, with symptoms of different severity. For example:

  • the lungs (in the bronchial system, a disruption of salt transport creates viscous mucus, which is responsible for chronic, bacterial infections and progressive destruction of the lung tissue),
  • the pancreas (growth and development disorders) and
  • the testicles (infertility, azoospermia)

To date, more than 1000 different CFTR mutations have been found in CF patients worldwide. A mutation screening can only record the most common mutations in the ethnic groups of the study area, but cannot rule out a mutation in general.