Other names for this test
This test might also be called:
- Whole genome microarray;
- Array comparative genomic hybridization; SNP Microarray
What are chromosomes?
Our body is made of billions of cells. Each cell has DNA. DNA carries the instructions for how our bodies work, grow and develop.
DNA is very long and is ordered into packages called chromosomes. Humans have 46 chromosomes arranged in 23 pairs in each of our cells.
A gene is a short length of DNA found on a chromosome.
What is a Chromosome Microarray Test?
The test checks for:
Chromosome deletion: to see if there is a missing piece of the chromosome
Chromosome duplication: to see if there is an extra piece of chromosome
If there is a change—an extra piece or a missing piece—genes might be affected depending on:
- Which chromosome has the change
- Where the missing or extra piece is on the chromosome
- How big or small the missing or extra piece is
Why has the Chromosome Microarray Test been offered?
This test might be offered if we think your condition might have been caused by a change to chromosomes.
This test might be offered if we think there may be there may be a genetic cause for your medical condition
This test might be offered if we have done some other medical tests and a physical examination (so looking, feeling, listening to different parts of the body), but we are still not sure what is causing your condition.
This test might be offered to someone who has difficulties with their learning or their physical development
How is the Chromosome Microarray test done?
The Chromosome Microarray test is usually a blood test.
How is the Chromosome Microarray test done?
A blood test is when some of your blood will be taken, usually from your arm, using a needle. Blood tests are usually done by a health professional e.g. a nurse.
Giving Consent
You need to give consent for this test to be carried out. Consent means giving your permission. You will need to sign a form to give your permission
With your consent, the laboratory (the place where your blood gets tested) will keep any leftover DNA. They might use this if more tests are needed in the future
What happens next?
It can take a few weeks for the tests to be completed and to get your results.
The consultant will get the results and talk to you about them. You can ask them any questions you have about the test or the results.
What are the possible results from the Chromosome Microarray test?
- Normal result—no change in the chromosome is seen. Sometimes a test can come back as a normal result but the condition might still be genetic. Your consultant will talk to you about this.
- A change in the chromosome – the test has found a change: a missing piece of a chromosome or an extra piece of a chromosome that will result in a diagnosis of a medical condition
- The test shows that there is a change in the chromosome but we do not know if this chromosome change is the reason for the medical condition (the medical term for this is Variant of Unknown Significance or VUS). To help them understand this type of result, your consultant may ask parents or other family members to have a blood test You can talk about this with your consultant if it happens.
Unexpected Information
There is a very small chance that the Chromosome Microarray test could pick up a different change that is not linked with the current medical condition.
This could possibly have an impact for the future health of you and your family.
If this happens, we will talk to you about the results and offer any further support and/ or tests you may need.
Will this test change my current medical care?
The microarray test is a way of trying to help us understand and manage your condition better.
If there is a diagnosis following the results of your test, it may change the way your medical condition is treated
- It might give us more information about your medical condition and signpost you to support groups. This might be helpful to you and your family.
- It might give us more information about the way your medical condition could change over time. We’d have more information about any other health problems linked to it. This might mean you would have more regular check ups.
- It might give us more information about the chances of the condition being passed to your children.
- It may give us information about the possibility of other family members being affected by the same genetic condition.
If you choose not to have the Chromosome Microarray test your medical care with still continue.
Where can I get more information?
Liverpool Centre for Genomic Medicine Liverpool:
Women’s Hospital NHS Foundation Trust Crown Street,
Liverpool, L8 7SS
Telephone: 0151 802 5001 or 5008
Email: [email protected]
North West GMSA site: https://www.nw-gmsa.nhs.uk
BBC bite-size: Chromosomes, DNA and genes: https://www.bbc.co.uk/bitesize/guides/znm66v4/revision/2