A chromosomal microarray (array) is a test that looks for any pieces of chromosomes that are missing and any pieces that are extra. These chromosome variants can sometimes cause health or learning concerns.

Your healthcare provider may suggest this test to look for a cause for your or your child's health or learning concerns.

An array is done on a sample of blood. It can give 4 kinds of results:

• Positive: The array found a causing a variant chromosome disorder for you or your child. Knowing this diagnosis can provide helpful information for you and your healthcare team.
• Negative: The array did not find anything. There could still be a genetic condition, but the array was not able to find it​.
• Uncertain: The array found a variant, but it is not well-understood. The change may or may not explain your health or learning concerns. Your healthcare team will talk with you about next steps to try to better understand this result.
• Incidental: The array found a chromosome disorder that is not related to your current concern. This can be surprising to learn about. Although an incidental finding does not explain your current concerns, it may still be medically important for you or your family.

One kind of incidental finding is consanguinity between the parents of the person being tested. Consanguinity is when parents are biologically related to each other. This means that the parents have a common ancestor, like having the same grandparent or great-grandparent. Consanguinity can be common in some communities, like when all members of a community are descended from a relatively small group of ancestors.

Because the array only looks for missing and extra pieces of genetic material, some genetic causes for health concerns cannot be found by this test. In some cases, your healthcare team might suggest a more detailed test to look at your genes.