Karyotyping: what is it, what diseases does it detect and why is it key in fertility? (2025)

The karyotype study is an essential genetic test to evaluate fertility in both men and women.

Its analysis makes it possible to detect possible chromosomal alterations that may be affecting reproductive capacity or increasing the risk of repeated miscarriages.

To understand in depth when it is advisable to perform this test, how it is carried out and what its results mean, we talked to Dr. Daniel Bodri, gynaecologist and fertility specialist at Vida Fertility, who explains its importance within assisted reproduction treatments.

Karyotyping refers to the complete set of chromosomes of an individual.

Karyotype analysis is an essential genetic test for patients who come to a fertility clinic after experiencing difficulties conceiving naturally. As such, it is considered a basic assessment in both female fertility and male fertility testing.

To determine a person’s karyotype, a blood sample is taken. From this sample, the lymphocytes are cultured in the laboratory until the chromosomes reach their maximum compactness, which allows them to be observed in detail under the microscope.

Karyotype analysis is used to identify alterations in chromosomes and detect possible genetic abnormalities. Applications include:

• To evaluate the presence of chromosomal disorders in the patient or their family in the following cases:
  • History of family genetic diseases.
  • Symptoms that could be related to a genetic disorder.
• Diagnose possible chromosomal alterations in a foetus during pregnancy.
• Determine if chromosomal abnormalities are affecting fertility, such as:
  • Male infertility
  • Female infertility
  • Repeated miscarriages or implantation failures
• Support diagnosis and guide treatment decisions in certain cancers and blood disorders.

Karyotype analysis is a key test in the study of fertility, as it allows the identification of alterations in the number and structure of chromosomes.

Among the most common numerical chromosomal abnormalities are:

• Klinefelter’s syndrome: Presence of an extra X chromosome (47, XXY).
• Turner syndrome: Missing X chromosome in females (45, X0).
• Down syndrome: Trisomy of chromosome 21 (47, XX, +21 or 47, XY, +21).
• Patau syndrome: Trisomy of chromosome 13 (47, XX, +13 or 47, XY, +13).
• Edwards’ syndrome: Trisomy of chromosome 18 (47, XX, +18 or 47, XY, +18).

In addition, karyotyping can detect alterations in chromosome structure, such as deletions, inversions and translocations. These abnormalities may be associated with reproductive problems, including recurrent miscarriages, ovarian failure and alterations in sperm quality in males.

Karyotype analysis provides information about the structure and number of chromosomes, but does not detect specific genetic mutations that cause monogenic diseases.

If karyotyping reveals chromosomal alterations, assisted reproduction techniques may be an option to achieve a healthy pregnancy. In these cases, in vitro fertilisation (IVF) with pre-implantation genetic diagnosis (PGD) or better known as PGT-A is recommended.

This procedure allows the eggs to be fertilised with the sperm in the laboratory and the embryos to be genetically analysed before being transferred to the uterus, ensuring that only those with a normal chromosomal endowment are implanted. Those with genetic abnormalities are discarded.

When more complex or severe chromosomal alterations are detected, gamete donation may be a viable alternative, thus ensuring a higher chance of successful treatment.

Karyotype analysis is a genetic test recommended in various situations to assess a person’s chromosomal health. It may be advisable in the following cases:

• If you are planning a pregnancy:
  • To detect whether you or your partner have chromosomal alterations that could be inherited to the baby.
  • To investigate possible causes of infertility or recurrent miscarriages.
  • To assess the risk of the foetus having genetic abnormalities, especially in pregnancies with risk factors such as:
• Advanced maternal age (35 years or older), as the risk of chromosomal alterations increases with age.
• Family history of genetic disease or presence of a genetic disorder in one of the parents.
• Abnormal prenatal screening test results.
• If you have a family history of chromosomal disorders:
  • Allows you to assess the possibility of developing a genetic disease or passing it on to future generations.
• If you or your child has symptoms of a genetic condition:
  • Depending on the symptoms and the type of disorder, a karyotype analysis can help confirm the diagnosis.
• If you have been diagnosed with certain types of cancer or haematological diseases:
  • Some cancers and blood disorders are linked to chromosomal alterations that can influence the diagnosis and the choice of the most appropriate treatment. These include:
• Leukaemia
• Lymphoma
• Multiple myeloma
• Anaemia

In short, karyotyping is a fundamental tool in reproductive and genetic medicine, helping to identify risks and make decisions about family planning.

Dr. Daniel Bodri answers:

• Normal or negative result: Indicates that the test has detected a total of 46 chromosomes with no structural or numerical alterations. This means that no chromosomal abnormalities have been identified.
• Abnormal or positive result: This means that changes in the number or structure of the chromosomes have been found. These alterations can have different implications for the health of the person or the baby, depending on the type of chromosomal change identified.

If the results show any abnormalities, it is essential to consult a genetics or assisted reproduction specialist to understand their impact and determine the next steps to take.

Dr. Daniel Bodri answers:

Karyotyping is an essential test for couples seeking reproductive assistance due to fertility problems. However, not all clinics routinely request it, but it is usually recommended in specific situations such as:

• Azoospermia (absence of sperm in the semen).
• Severe oligozoospermia (low sperm concentration).
• Embryo implantation failure after assisted reproduction treatments.
• Recurrent miscarriages, when there have been several consecutive gestational losses.

If you have doubts about whether you need this test, it is best to consult a fertility specialist who can guide you according to your specific case.

• Female fertility tests
• Male fertility tests
• Causes of infertility
• Hormones and fertility
• When to see a specialist