In a man, changes in individual genes may be a cause of a significantly reduced sperm count, i.e. oligozoospermia or azoospermia. Here, a distinction is made between obstructive (occlusion or absence of the sperm ducts) and non-obstructive (absence of sperm production) oligozoospermia or azoospermia.
An obstructive azoospermia can be genetically determined and ascribed to a genetic abnormality in the sperm ducts. Men in whom the sperm duct is missing have a 60 to 70 % chance of a mutation for cystic fibrosis (so-called muscoviscidosis) in the CFTR gene. Muscoviscidosis is a hereditary disease which is associated with pulmonary and pancreatic changes.
Mutations in the CFTR gene can be discovered with the help of a molecular genetic analysis. If there is evidence of a mutation in a healthy man with azoospermia or oligozoospermia, there is an increased risk that his children produced by artificial insemination will suffer from cystic fibrosis.
Therefore, molecular genetic examinations of the CFTR gene are performed by us in connection with a human genetic consultation, in which the individual risks for subsequent children are discussed and weighed up and further genetic tests on the mother are taken into consideration.
In approximately 10 % of all men with non-obstructive oligozoospermia or azoospermia, missing gene regions (deletions) are found in the Y chromosome. The gene region in question is referred to as an AZF gene region (AZF: azoospermia factor).
With the help of the methods of reproductive medicine, it is possible to fulfil the desire to have children of men with a deletion in the AZF gene region. However, sons carry the deletion on their Y chromosomes like their fathers and will later also have oligozoospermia or azoospermia.
Here too, molecular genetic diagnosis takes place as part of a human genetic consultation.
In women, genetic mutations are a possible cause for repeated miscarriages (habitual miscarriages).
Mutations in the coagulation factor V and prothrombin (factor II) mean an increased risk of thrombosis or embolisms. In the event of pregnancy, women with such a mutation are prone to miscarriages. This can be prevented with a heparin treatment.
Women with mutations in the gene for methylenetetrahydrofolate reductase (MTHFR) can have low folate levels in the blood, which, in the event of a pregnancy, may lead to neural defects (open spine) in the child and to miscarriages. In this case, the ingestion of folic acid during pregnancy is the best prophylaxis.