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Karyotyping: How chromosome analysis helps understand health
«Why can’t we have a child?» is often where the path to karyotyping begins.
Couples who have been trying to get pregnant for a long time, women after miscarriages, parents of a child with genetic abnormalities - they are the ones who most often learn about the study called karyotyping. This test does not show glucose levels or hormones – it shows architecture of human chromosomes, that is, the deepest level of our body's structure. Sometimes it is there - in changes invisible to the eye - that the cause of many medical problems lies.
What is karyotyping?
Karyotyping is cytogenetic study, which allows you to see the number, shape, and structure of chromosomes in human cells. Normally, a person has 46 chromosomes (23 pairs), of which one pair determines sex (XX in women, XY in men).
The study allows to identify:
extra or missing chromosomes
translocations (exchange of regions between chromosomes)
inversions (fragment flipping)
duplications or deletions (excess or missing parts of DNA)
When is karyotyping prescribed?
Infertility or repeated miscarriages
Planning a pregnancy after 35 years
Suspicion of genetic disorders in the child
Congenital malformations
Mental or physical developmental delay
Abnormalities of sexual development
Presence of hereditary diseases in the family
Suspicion of chromosomal diseases: Down syndrome, Turner, Klinefelter
How the research is done
Venous blood sampling
Lymphocyte isolation – cells that divide rapidly
Treatment with drugs that stimulate mitosis
Cell fixation and chromosome staining
Microscopic study of chromosomes and construction of a karyogram – schematic representation of chromosomes
The procedure is not painful. The result is usually ready within 10–14 days, as it takes time for the cells to grow in the laboratory.
What can a karyotype show?
| Type of violation | Example | Consequences |
|---|---|---|
| Trisomy | 47,XX,+21 (Down syndrome) | Mental retardation, heart defects |
| Monosomy | 45,X (Turner syndrome) | Short stature, infertility |
| Translocation | t(14;21) | Genetic instability, risk to offspring |
| Inversion | inv(9)(p11q13) | Often asymptomatic, but can affect fertility |
| Mosaicism | 46,XX/47,XX,+18 | Partial form of trisomy, variable clinical picture |
Karyotyping in reproductive medicine
In 30–50% cases of miscarriage, genetic disorders in the embryo, which are incompatible with life. Karyotype analysis in parents helps to detect hidden translocations or mutations that could be transmitted to the child. This study is also important before IVF programs - to select embryos without chromosomal defects (using PGT).
Limitations of the method
Does not detect point mutations in genes – this requires molecular analysis
Does not show metabolic or functional disorders
Requires lengthy sample preparation – therefore not used for rapid diagnosis
What to do after receiving the result
The interpretation of the karyotype should be carried out by clinical geneticist. The detection of structural rearrangements does not always mean pathology - in some people they may be without clinical manifestations (the so-called variants of the norm). If the changes confirm the risks to the offspring, the doctor may suggest:
re-examination
family geneticist consultation
prenatal or preimplantation diagnosis
genetic testing of the partner
Karyotyping is not just a «check-box analysis.» It medical map of chromosome structure, which can provide answers to questions that have remained unexplained for years.
