Your doctor has ordered a special chromosome test, called a microarray, because you, your child, or someone in your family may have a genetic condition. Some genetic conditions may be caused by a change in the chromosomes.
Chromosomes and Genes
The human body is made of up millions of tiny cells. Inside each cell is a set of chromosomes. Chromosomes are long strands of genetic material that contain our genes. Genes tell the body how to grow and develop.Each person should have 23 pairs of chromosomes (46 total). One chromosome of each pair is inherited from a person’s mother; the other chromosome in each pair is inherited from a person’s father. In order for the body to grow and develop correctly, most individuals must have two copies of every chromosome and two copies of almost every gene. When a person has extra or missing genes, it can affect how a person grows and develops.
The Microarray Analysis
To determine whether or not a person has extra (duplicated) or missing (deleted) genes, a microarray analysis is done. This test uses a small blood sample to look closely at a person’s chromosomes. It can detect small changes in the chromosomes called duplications (extra genetic material) or deletions (missing genetic material). The test takes approximately three-four weeks to complete.
Possible Results
A normal result means that no duplications or deletions of genetic material were found.
A likely pathogenic result means that a duplication or deletion of genetic material was found, and this is likely to cause health or learning problems. Your doctor might be able to make predictions on how this genetic change will affect a person.
A likely benign result means that a genetic change was found, but it is not likely to cause health or learning problems. Every person has slight differences in his or her genes. These differences make each person individual and unique. Benign changes (duplications or deletions that do not cause learning or health problems) are part of normal human variation.
A variant of unknown significance is a genetic change that has not been reported before in other individuals. It is unclear whether the genetic change might cause learning or health problems, or if it is benign (a change that does not cause learning or health problems).
When a variant of unknown significance is found on microarray, the lab recommends testing the parents to see if either of them has the same genetic change.
- If either parent is found to have the same genetic change and has no learning or health concerns, then the variant is more likely to be benign (not causing any problems).
- If the parents are not found to have the same genetic change, it is still difficult to tell whether the change is normal human variation or if it could cause any health or learning problems. In these cases, we watch to see if any other individuals are reported with a similar genetic difference. Over time we may learn more about what this change means.
After the results of the microarray test are back, your doctor will talk to you about the results. If you have any further questions, please call the Genetics Department at 614-722-3535.