Chromosome Microarray

Is Testing Right for Me? I Have My Test Results

Chromosome Microarray

Resources

Chromosome Disorder Outreach
Link: http://www.chromodisorder.org/CDO/
This US-based non-profit group provides information and support for families affected by rare chromosome disorders. Their registry of chromosome disorders catalogs changes found and is divided by chromosome. Their site also offers a family listserv, an "Ask the Doctor" forum, and a reference library.

Unique: Rare Chromosome Disorder Support Group
Link: http://www.rarechromo.org/html/home.asp
This support and advocacy group for patients and families affected by rare chromosome disorders is based in the United Kingdom but welcomes members worldwide. Their "Little Yellow Book" provides a basic overview of chromosomes and rare chromosome disorders and is available in five languages.

Genetics Home Reference: Microarray Definition
Link: http://ghr.nlm.nih.gov/glossary=microarraytechnology
This site, sponsored by the National Library of Medicine, provides a basic definition of chromosome microarray (CMA) testing.

Talking Glossary of Genetic Terms: Microarray Technology
Link: http://www.genome.gov/glossary/index.cfm?id=125
This site, sponsored by the National Human Genome Research Institute, has an explanation of CMA presented on video by an expert.

Next: References

Why are you considering testing?

I am considering testing for my child who has signs and symptoms of developmental delay and/or autism, but hasn't been diagnosed for sure yet.

I am considering testing for my child who has developmental delay, mental retardation, birth defects and/or other unusual physical features without a known cause.

I am considering testing for my child who has an autism spectrum disorder.

I'm pregnant and considering testing because of birth defects found on ultrasound.

I lost a pregnancy (miscarriage or stillbirth) with birth defects.

None of these.

Chromosome microarray (CMA) testing and other genetic testing can be part of the evaluation for developmental problems, but it isn't the first step.

Evaluations may be needed with doctors and sometimes other specialists to decide whether your child has a health or learning problem. There are many different causes for developmental problems. Doctors need to consider the big picture, and review your child's birth history, medical history, do a head-to-toe exam, and decide what testing might be needed.

Chromosome microarray testing may be useful for your child.

About 10% to 20% of children with mental retardation/intellectual disability, developmental delay, birth defects and other unusual features have a chromosome change that can be found with this testing.

If a chromosome change is found, it is the likely cause of your child's problems. Testing is very accurate. Having information about your child's specific deletion and/or duplication can help guide healthcare decisions. Testing may be useful for other family members (including you as the parent) who are concerned about their reproductive risks.

If no chromosome change is found, a genetic cause of your child's problems can't be ruled out. There may be other changes in genes or chromosomes that can't be found with this testing. There are hundreds of known genetic syndromes that are not checked for with this test.

It is possible to get results from testing that are uncertain. Sometimes chromosome changes are found, and they've never been found before or it's not clear whether they have an effect on development. In order to get more information, testing may be done on both parents to decide whether the change was inherited or is new. Doctors may be able to do research to find out whether the change has been reported in other people and how they were affected by it. However, there are times when a clear answer can't be reached, even with extra testing and research.

Chromosome microarray testing may be useful for your child.

About 7% to 10% of children with autism will have a chromosome change found with testing.

If a chromosome change is found, it is the likely cause of your child's problems. Testing is very accurate. Having information about your child's specific deletion and/or duplication can help guide healthcare decisions. Testing may be useful for other family members (including you as the parent) who are concerned about their reproductive risks.

If no chromosome change is found, a genetic cause of your child's problems can't be ruled out. There may be other changes in genes or chromosomes that can't be found with this testing. There are hundreds of known genetic syndromes that are not checked for with this test.

It is possible to get results from testing that are uncertain. Sometimes chromosome changes are found, and they've never been found before or it's not clear whether they have an effect on development. In order to get more information, testing may be done on both parents to decide whether the change was inherited or is new. Doctors may be able to do research to find out whether the change has been reported in other people and how they were affected by it. However, there are times when a clear answer can't be reached, even with extra testing and research.

Chromosome microarray testing may be useful for your pregnancy.

Overall, about 1% to 3% of pregnancies with birth defects have abnormal test results on chromosome microarray (CMA) when regular chromosome analysis results are normal. Testing may provide you an answer about the cause of the birth defects in your pregnancy. It may give you some answers about what you might anticipate for the future.

If a chromosome change is found, it is the likely cause of birth defects in your pregnancy. Testing is very accurate when a chromosome change is found. Having information about the specific deletion and/or duplication can help guide healthcare decisions. Testing may be useful for other family members (including you as the parent) who are concerned about their reproductive risks.

If no chromosome change is found, a genetic cause of birth defects in your pregnancy can't be ruled out. There may be other changes in genes or chromosomes that can't be found with this testing. There are hundreds of known genetic syndromes that are not checked for with this test.

It is possible to get results from testing that are uncertain. Sometimes chromosome changes are found, and they've never been found before or it's not clear whether they have an effect on development. In order to get more information, testing may be done on both parents to decide whether the change was inherited or is new. Doctors may be able to do research to find out whether the change has been reported in other people and how they were affected by it. However, there are times when a clear answer can't be reached, even with extra testing and research.

If not already done, your doctor may also order a chromosome analysis (also called a karyotype). Around 16% to 30% of pregnancies with birth defects have a larger chromosome change that can be found with that testing. Chromosome analysis sees the "big picture" while CMA finds smaller changes. These two tests each have their benefits and limitations, so doctors use these tests in different ways.

If you've already had prenatal testing done by chorionic villus sampling (CVS) or amniocentesis, you probably won't need to have another procedure done to have CMA testing. Most of the time, the laboratory that handled the original sample can send cells for CMA, if they don't perform the testing themselves.

Chromosome microarray testing may be useful for you.

Testing may provide you an answer about the cause of the birth defects in your pregnancy and whether there is a higher chance for it to happen again. Chromosome microarray (CMA) is usually only done when birth defects are found because pregnancy losses for other reasons are common.

If a chromosome change is found, it was the likely cause of birth defects in your pregnancy. Testing is very accurate. Having information about the specific deletion and/or duplication can help provide an understanding of what caused the birth defects. Testing both parents will be useful to give accurate recurrence risks.

If no chromosome change is found, a genetic cause of birth defects in your pregnancy can't be ruled out. There may be other changes in genes or chromosomes that can't be found with this testing. There are hundreds of known genetic syndromes that are not checked for with this test.

It is possible to get results from testing that are uncertain. Sometimes chromosome changes are found, and they've never been found before or it's not clear whether they have an effect on development. In order to get more information, testing may be done on both parents to decide whether the change was inherited or is new. Doctors may be able to do research to find out whether the change has been reported in other people and how they were affected by it. However, there are times when a clear answer can't be reached, even with extra testing and research.

If not already done, your doctor may also order a chromosome analysis (also called a karyotype). Chromosome analysis sees the "big picture" while CMA finds smaller changes. However, it is sometimes technically difficult to do chromosome analysis on a sample from a pregnancy loss or stillbirth. If chromosome analysis can't be done, CMA can be done alone and still provide useful information.

Depending on the circumstances of your pregnancy loss, fetal autopsy may also be an option. A complete autopsy can often provide answers about the likely cause of birth defects, even if genetic testing is normal.

Chromosome microarray testing may not be useful for you. The main reasons for testing are listed in the Who Should Consider Testing? section.

CMA testing is sometimes used for other health problems, especially cancer. Those uses are not covered by this tool.

If you have a reason for testing that isn't covered here, talk to your doctor or a genetic counselor about whether testing might be useful for you.