If you have been trying to have a baby for a long time, it is important to find out why. There are many reasons for infertility and miscarriage, which can be medical or psychological. External factors such as stress, obesity or an unhealthy lifestyle can also play a role. And it is not uncommon for genetic defects to lead to infertility. Have you been trying for months to get pregnant or have you had a miscarriage? The reason for your fertility problem could be genetic - find out more here.

Chromosomal abnormalities as a cause of infertility

Our bodies contain countless cells, each of which has a nucleus. This nucleus contains all our genetic material, which is made up of deoxyribonucleic acid. We know it by the common name DNA. During cell division, it takes the form of chromosomes. The chromosome set of a healthy person consists of 22 pairs of chromosomes plus a pair of sex chromosomes (XX for female and XY for male), making a total of 46 chromosomes.

In about 10 per cent of couples who wish to have children, one of the partners is diagnosed with a chromosomal translocation. This means that individual DNA segments within the chromosome pairs are shifted or swapped. As a result, the affected gene may be present twice on one chromosome and absent on the other. Such a genetic defect has no physical consequences for the affected person, as all the genetic material is present in all the cells, just in the wrong place. This is called a balanced translocation. However, this genetic defect leads to incorrect combinations of genetic material during the formation of gametes. In women, this means that when chromosomes divide, the genetic information is passed on in the wrong order during egg cell formation. If fertilisation does occur, the fertilised egg may not be viable and may not implant in the uterus. And if implantation does occur, the embryo's development is so disturbed that an early miscarriage is likely. Women with a chromosomal translocation therefore have an increased risk of miscarriage. If the pregnancy continues, the baby is very likely to have a physical or mental disability. The chromosome translocation in the child is called an unbalanced translocation. Depending on which gene is affected, the baby is not viable as an embryo or is born with a health condition.

As well as a translocation, there is another type of chromosomal change, which is a change in the number of chromosomes. In some people, instead of 46 chromosomes, there are either 47 or only 45 chromosomes. The former is called trisomy (the duplication of a chromosome) and the latter is called monosomy (the absence of one chromosome in a diploid set of chromosomes). In women with Ullrich-Turner syndrome, one of the X chromosomes is partially or completely missing, which leads to malformation of the female gametes. As a result, the ovaries do not develop and the woman remains infertile. Ullrich-Turner syndrome is therefore a chromosomal disorder that only occurs in women.

Other fertility problems in women

The genetic defects mentioned above can occur in both sexes. There are also two types of fertility disorder that are actually only found in women:

POI: Premature Ovarian Insufficiency

This is the term for premature menopause in women. POI is caused by a mutation in the FMR1 gene and other, rarer gene mutations that cause the ovaries to stop functioning prematurely.

Adrenogenital syndrome

This genetic defect is a disorder in the production of hormones responsible for female fertility, which are produced in the adrenal cortex. It is caused by a change in the CYP21A2 gene.

When advice is needed

Have you been trying for several months to get pregnant, but your pregnancy test has come back negative? Don't be discouraged, you don't have to accept your fate. Modern medicine has a number of methods to help you find the reason for your infertility. In many cases, it also offers appropriate treatment options. It is important that both partners are examined. This is because conditions such as chromosomal abnormalities can occur in both men and women and affect fertility in both sexes.

It is also advisable for partners to seek help early on so that any disorder can be treated in time - ideally if there is no pregnancy after one year. Special tests are needed to find out if there is a genetic defect and what it is. For example, it is thought that 80 per cent of all miscarriages that occur before the expected bleeding are due to a chromosomal translocation. If you are trying to have a baby and have had several miscarriages, experts recommend that you and your partner have a chromosome analysis. A genetic mutation in the child that leads to a single miscarriage usually occurs for no apparent reason. On the other hand, three or more spontaneous miscarriages are suspicious.

What are the diagnostic procedures?

Today, there are several ways to detect a genetic defect. Modern diagnostic procedures can even detect an increased risk of disability in the baby at an early stage. A human genetic counselling service under the Genetic Diagnostics Act would be the first port of call for you and your partner to find out if a test is an option for you. Before the actual diagnostic procedure, a doctor or specially trained expert will give you information about the possible causes of childlessness and infertility. He or she will then explain the different treatment options and how they work. Only after you have given your written consent will a diagnostic procedure be carried out.

The different diagnostic procedures include

• Chromosome analysis (cytogenetics): The test is done by taking a simple blood sample. The blood sample is used to examine the chromosomes for abnormalities under a microscope. The number and structure of the chromosomes are then shown on a karyogram. Chromosome analysis is not only used to find the causes of miscarriages or infertility, but also to diagnose hereditary diseases. It is also used in prenatal diagnosis to detect genetic disorders in the unborn child at an early stage.
• Molecular genetic techniques: These methods can detect genetic diseases caused by mutations in DNA sequences. Using next-generation sequencing (NGS), several genes can be examined in parallel.
• Invasive prenatal diagnostics such as chorionic villus sampling or amniocentesis: These are used when there is a genetic risk during pregnancy. These tests examine the unborn child's chromosomes for disorders. If the baby has one chromosome too few or too many, the embryo may not be viable. In some cases, a miscarriage may be expected.

Treatment options

If you do not want to accept the unfulfilled desire to have children as fate, but want to actively do something, there are various treatment options available:

• In vitro fertilisation (IVF) with or without intracytoplasmic sperm injection (ICSI)
• Sperm transfer (insemination)
• Egg donation and / or sperm donatio
• Embryo adoption
  

Your physician will discuss which treatment is right for you with you and your partner.