Chromosome Microarray

Is Testing Right for Me? I Have My Test Results

Chromosome Microarray

Who Should Be Tested with Chromosome Microarray?

Chromosome microarray (CMA) testing may be used for:

  • People with developmental delay or mental retardation of unknown cause
  • People with multiple birth defects
  • People with unusual features that don't look like other family members
  • People with autism spectrum disorders
  • Pregnancies with birth defects found by prenatal ultrasound
  • Pregnancy loss (miscarriage or stillbirth) with birth defects

CMA testing is sometimes the first test done for people who have these developmental issues. It will identify a cause in about 10-20% of people with developmental delay or mental retardation, and about 7-10% of people with autism spectrum disorders.

There are many reasons to look for a cause of these health and learning problems with CMA testing. While finding a cause doesn't cure or fix the problems, it can:

  • Provide an answer about why the person has these signs and symptoms
  • Give you and your doctor information about what to expect in the future
  • Improve health screening and prevention for some conditions
  • Allow for testing of family members
  • Give you accurate information about the chances to have another affected child
  • Let you connect with other families and get support services from schools and community
  • Explain why a pregnancy loss happened

Definitions

It is important to understand the ways that doctors and other professionals describe and diagnose some of the health and learning problems that can be caused by chromosome changes.

Developmental delay (DD) happens when a young child has a lag or slowness in reaching milestones like sitting, walking, and talking compared to other children the same age. Delays can be in only one area – like talking, thinking, moving, or interacting. They can also be more "global," affecting more than one set of skills. DD is usually used for children under 5 years old. About 1% to 3% of children have DD. Some children with DD will have mental retardation, while others will "catch up" to their peers and have typical learning later in childhood.

Mental retardation (MR), also called intellectual disability (ID), is defined by the World Health Organization based on tests of intelligence (IQ tests). An IQ score of less than 70 is considered MR. MR can be divided into types: mild (IQ 50-70), moderate (IQ 35-50), severe (20-35), and profound (<20). About 1% to 3% of people have MR. Mild MR is much more common than moderate or severe MR.

A birth defect is an abnormality of the way a body part is formed or how it works. Thousands of different birth defects have been identified, but some common ones include cleft lip and palate, spina bifida, and heart defects. Some people have one birth defect, while others have more than one.

Autism and autism spectrum disorders (ASD) are a group of conditions defined by difficulties with social interaction, communication, and unusual behaviors. There is a wide range of how a person can be affected with an autistic disorder. The spectrum includes people with autism, Asperger syndrome, and pervasive developmental delay (PDD).

Next: How Chromosome Microarray Testing Works

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.