At the fertility surgery we offer a range of tests that provide couples with a comprehensive genetic assessment. The type of genetic test carried out will depend on the family history or disorders that the patients may suffer from.
Cytogenetic testing: such as conventional karyotyping and molecular karyotyping which detect the presence of chromosomal abnormalities. Chromosomal abnormalities are involved in the aetiology of infertility in a significant number of cases.
Molecular genetics: For example, we use these tests for:
- Genetic screening for hereditary diseases. This allows us to detect a defective gene implicated in a particular disease, making it possible for us to extend genetic testing to relatives at risk, and carry out predictive prenatal or preimplantation tests.
- Within molecular genetics, a special mention must be made of the mass sequencing techniques which have revolutionized genetic screening over the last ten years. These techniques allow us to obtain information from multiple genes in a very short time. Thanks to these techniques we are able to carry out a genetic carrier screening. This is particularly important for couples before they begin to try to get pregnant to determine whether or not either of them is a genetic carrier of hereditary diseases, and so to be able to offer them an accurate genetic assessment. These techniques are also especially significant in the diagnosis of a broad range of heterogeneous genetic disorders.
The next step in genetic carrier screening is to test for gene mutations that cause genetic disorders.
- Autosomal recessive diseases occur when two mutant copies of the same gene are inherited. For this to happen both the father and the mother must be carriers of the disorder. A carrier of a mutant gene that causes a recessive disease does not manifest the symptoms of that disease. In effect we are all carriers of recessive diseases that we have never suffered from. Where both partners are carriers of recessive mutation in the same gene there is a 25% chance that their children will be affected by the disease.
- In the case of recessive diseases linked to the X chromosome, the causative gene is found in the sex chromosome. Women have two X chromosomes, and if there is a mutation in one of them, the woman affected will not suffer from the disease herself, but she will be a carrier. 50% of the offspring of a woman who is a carrier will inherit a copy of the mutant gene. If that mutant gene is passed on to a man, he will suffer from the illness as men have only one X chromosome. If on the other hand the mutant gene is passed on to a woman, she will become a carrier.
Where a risk of transmission has been detected, this information can help a couple with family planning, as there are different options that can minimise risk, and permit them to have children who will be free of the disorder.