When parents find out that their child has hearing loss, one of the first questions they ask is often, “Why?”
Some causes of hearing loss are easy to determine: the child has outer or middle ear malformations that are apparent in a visual examination, the mother had an illness known to cause hearing loss during pregnancy, or the child suffered some trauma at birth related to hearing loss (for example, many premature babies are given ototoxic drugs that keep them alive at the cost of damaging their hearing). But other cases are not so clear-cut.
Genetic testing for hearing loss involves drawing a small amount of blood, which is then sent to a lab an analyzed at a genetic level. There are several common tests on the market. You might hear names like OtoSCOPE®, OtoGenome™, OtoChip™, or OtoSeq™, all of which are different companies’ tests that scan your child’s genes for a number of mutations associated with hearing loss. Often, insurance will cover all or part of the cost of the test.
Families choose to undergo genetic testing for many reasons. The test results can help families make decisions about future children, or give them information to share when their children reaches the age to have children of their own. Even if a family knows that they would have more children regardless of the results of the genetic testing, the information gained can still benefit the family and their current and future children. It can identify syndromes and make families aware of other associated symptoms that may need further testing. For example, a child may present as “just deaf” but genetic testing could show that the child has a syndrome that also affects the kidneys, alerting parents that additional testing is needed to ensure the child’s health, even though no symptoms are apparent at the present time. Some syndromes have conditions that may not be present at birth but may develop or deteriorate over time (for example, progressive hearing and/or vision loss in Usher Syndrome or, for other syndromes, endocrine problems that may present at puberty).
Other families pass on genetic testing. It is possible that the tests will not identify a genetic cause of hearing loss, and the family does not want to go through the cost and effort with no gurantee of results. Other families would not change their family planning decisions regardless of the results, so choose not to undergo the test. Some parents wish to give their child the choice whether or not to find out the cause of their hearing loss when the child is older.
Keep in mind that choosing to have genetic testing does not automatically guarantee results. Of children born with profound hearing loss, approximately 25% have hearing loss of unknown cause (idiopathic) and 25% from non-genetic causes (injury, illness, etc.). Of the 50% with genetically-caused hearing loss, 30% of those causes are syndromic, meaning the hearing loss occurs along with a constellation of other issues. For the remaining 70%, the hearing loss is the only effect of the genetic mutation. Remember, too, that just because the genetic testing did not determine a cause of hearing loss, this does not mean that the child’s hearing loss is not genetic, just that we do not yet have a name for the mutation or syndrome that caused the hearing loss… yet. Years from now, what seems like a random mutation may turn out to be linked to a known cause of hearing loss or a newly identified syndrome.
Ultimately, knowing the cause of a child’s hearing loss provides us with important new information, but that information alone does not change the course of our therapy or the techniques we use to teach listening and spoken language. Just as each family chooses the communication method that is right for them, each family must also make their own, well-researched decision before they choose genetic testing.
Here are some additional resources to help you make your decision:
A Parent’s Guide to Genetics and Hearing Loss from the Centers for Disease Control and Prevention (CDC)
Genetic Testing and Hearing Loss: Review and Case Studies by Dr. Aparna Rao, et. al (Audiology Online free course)
Genetic Testing for Childhood Hearing Loss: parent information booklet from the University of North Carolina