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Karyotyping: a picture of your chromosomes, not your genes | CION Cancer Clinics
Karyotyping is a picture of your chromosomes, arranged in matched pairs under a microscope. It does not read the letters inside a gene; it shows whether a whole chromosome is missing, extra, or has swapped a piece with another. This page explains when doctors still order it, how a normal result differs from a normal gene test, and where it fits in cancer care today. At CION Cancer Clinics in Hyderabad, our oncologists review your family history with you and guide you to the right genetic counselling and testing.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What is karyotyping, and why is it still requested?
- When would a doctor request a karyotype today?
- How is a karyotype actually made?
- The words this report uses, in plain language
- Karyotyping or gene sequencing: what is being looked for?
- What this page cannot tell you
- Four things people assume about karyotyping
- Common questions about karyotyping
The short answer
What is karyotyping, and why is it still requested?
Karyotyping is a picture of your chromosomes, taken under a microscope and arranged in matched pairs by size and shape. It does not read individual letters of DNA. It shows the bigger structure: whether a chromosome is missing, extra, broken, or joined to the wrong partner. That bigger view is something no panel test replaces.
What it is actually looking for
Most inherited cancer testing looks for a small spelling change in one gene. Karyotyping looks for something larger: a whole chromosome that is missing or duplicated, or a piece of one chromosome that has swapped places with a piece of another. These large changes can raise cancer risk or explain a pattern of pregnancy loss and developmental differences in a family.
Where it still fits today
Newer tests read genes in far more detail, but they are not built to see the whole chromosome picture at once. When a family history suggests a structural rearrangement, or when a blood cancer needs to be classified by what has happened to its chromosomes, karyotyping is still the test used, sometimes alongside a molecular test rather than instead of one.
Karyotyping and gene sequencing answer different questions. A normal result on one does not mean the other is unnecessary.Where it is used
When would a doctor request a karyotype today?
It is a specific tool for a specific kind of question, not a general first test for cancer risk.
Classifying certain blood cancers
Some leukaemias and related blood conditions are grouped and treated differently depending on which chromosome changes are found in the cancer cells. Karyotyping of the bone marrow sample is part of that classification.
A family history of rearrangements
If a parent carries a chromosome piece that has swapped position without being lost, they can be entirely well themselves while passing an unbalanced version to a child. Karyotyping is how this is found and tracked through a family.
Often raised after
- Repeated pregnancy loss in the family
- A child with unexplained developmental differences
- A relative already known to carry a rearrangement
Alongside a bone marrow test for cancer
In some cancers of the blood and lymph system, the chromosome pattern in the cancer cells themselves guides which treatment is offered, separate from any inherited fault the person may or may not carry.
Why the distinction matters to you
If you have been offered karyotyping, it is because a structural question is being asked, not a spelling one. Ask which of these two it is if you are unsure, because the next steps differ.
Not sure whether this applies to you?
Ask an oncologistBehind the scenes
How is a karyotype actually made?
Growing the cells
Cells from a blood sample, or occasionally bone marrow, are grown in the laboratory until they are dividing, because chromosomes are only visible clearly at that point.
Stopping cell division mid-way
A chemical is added to halt the dividing cells at the exact stage where chromosomes are most tightly packed and easiest to see.
Staining and photographing
The chromosomes are stained with a dye that creates a pattern of light and dark bands, then photographed under a microscope.
Arranging and reading
A trained analyst arranges the chromosomes into matched pairs by size and banding pattern, then checks the arrangement for anything missing, extra, broken or rearranged.
On your report
The words this report uses, in plain language
- Chromosome
- A tightly packed bundle of DNA. A typical human cell has a matched set inherited from each parent.
- Translocation
- A piece of one chromosome has swapped places with a piece of another. Balanced means nothing is lost; unbalanced means something is.
- Deletion
- A piece of a chromosome is missing.
- Duplication
- A piece of a chromosome is present in extra copies.
- Balanced carrier
- Someone whose rearrangement has lost no genetic material and who is usually well themselves, but can pass an unbalanced version to a child.
- Banding pattern
- The light and dark stripes a stain produces on a chromosome, used to identify it and spot changes.
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Side by side
Karyotyping or gene sequencing: what is being looked for?
Karyotyping
Gene sequencing
Looks at whole chromosomes under a microscope
Reads the letters within a gene
Finds large, structural changes
Finds small, single-letter changes
Used for certain blood cancers and family rearrangements
Used for most inherited solid-tumour cancer testing
A normal result does not rule out a gene-level fault
A normal result does not rule out a chromosome-level change
Being straight with you
What this page cannot tell you
It cannot tell you whether you need a karyotype at all. That decision rests on why the test is being considered: a blood cancer that needs classifying, or a family pattern that suggests a structural rearrangement. Both need a specialist to interpret, not a general description.
It cannot substitute for gene sequencing
A normal karyotype does not mean your genes have been checked letter by letter. The two tests look for different things, and a family with a suspected inherited cancer gene usually needs sequencing, not karyotyping, unless a structural question has also been raised.
Who this does not apply to
Most people being tested for an inherited cancer risk do not need a karyotype. It is requested for a specific reason, usually recurrent pregnancy loss, a child with developmental differences, or a blood cancer being classified, not as a routine part of cancer genetic testing.
If a karyotype has been suggested and you are unsure why, ask directly what structural question it is meant to answer.Commonly believed
Four things people assume about karyotyping
"A karyotype checks all my genes for cancer
risk."
It checks the structure of whole chromosomes, not the letters inside genes. Most inherited cancer faults are spelling changes far too small for a karyotype to see.
"If my karyotype is normal, my genes must be
fine."
A normal karyotype rules out large structural problems, not small gene-level faults. A separate sequencing test is needed to check the letters within a gene.
"A balanced rearrangement means nothing was
lost, so it cannot matter."
The person carrying it is usually well, because nothing is missing in them. It can still matter for their children, who may inherit an unbalanced version with material genuinely missing or extra.
"Karyotyping is outdated and no longer
useful."
It remains standard for classifying certain blood cancers and for spotting family rearrangements that gene sequencing is not designed to see. It has a narrower job today, not a smaller one.
Questions we are asked
Common questions about karyotyping
Is karyotyping the same as genetic testing for cancer
genes?
No. Karyotyping looks at the structure of whole chromosomes under a microscope. Testing for inherited cancer genes reads the letters inside specific genes, which is a different, more detailed kind of test.
What sample is used for a karyotype?
Usually a blood sample. For certain blood cancers, a bone marrow sample is used instead, because the chromosome pattern inside the cancer cells is what needs to be seen.
Why would my child be offered karyotyping?
It is often requested after unexplained developmental differences, or when a parent is already known to carry a chromosome rearrangement. It looks for structural changes rather than single gene faults.
Can a karyotype find the gene fault behind a family
cancer syndrome?
Only if that syndrome is caused by a large structural change big enough to see under a microscope. Most inherited cancer syndromes are caused by a small spelling change, which needs gene sequencing, not karyotyping, to find.
What does "balanced translocation" mean on a
report?
It means a piece of one chromosome has swapped with a piece of another, but nothing is missing overall. The person carrying it is usually unaffected, though children can inherit an unbalanced version.
How long does a karyotype result take?
Longer than many blood tests, because cells must be grown in the laboratory until they are dividing before they can be examined. Ask the laboratory doing your specific test for their expected timeline.
Is karyotyping used in leukaemia care?
Yes. The chromosome pattern found in a bone marrow sample is part of how several blood cancers are classified, and it can influence which treatment is recommended.
Where do I start if a karyotype has been suggested for
my family?
Ask the doctor or counsellor who suggested it exactly what structural question it is meant to answer. Call the CION helpline if you would like it explained again in simpler terms.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
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Sources
- MedlinePlus Genetics — What is a chromosome?
- National Cancer Institute — NCI Dictionary of Genetics Terms: Karyotype
- GeneReviews (NCBI) — Genetic Testing: Overview
- Cancer Research UK — Chromosome and gene changes in cancer
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Chromosomal microarray explainedA more detailed way of scanning for structural changesFISH testing in geneticsAnother way of looking directly at chromosomesLarge genomic rearrangements and why panels can miss themWhy gene panels need a different test for structural changesWhich test would your situation need?Matching the right test to the right family question
Talk to us
Been asked to get a karyotype and not sure why?
Tell us what your doctor said and we will help you understand what question the test is actually answering. One helpline serves every CION centre.