Hello, my name is Kristal Platt. I'm a genetic counselor at Boys Town National Research Hospital working in the pediatric hearing clinic. Today I'm going to speak with you about genetic testing for individuals who are deaf and hard of hearing.
I'll be talking about how we think about hearing loss, the logistics for genetic testing and possible results. So I want to talk briefly about the reasons that families might consider doing genetic testing.
Probably the most common question I get is, will my child's hearing loss worsen? And the best way to answer that question is through genetic testing. Once we know the cause, we can answer that question as well as for a child who may be a candidate for cochlear implants.
Once we know the genetic explanation, we can go to the literature to see how have other individuals done once they received cochlear implants. We can also help answer the question whether or not an individual may have more health or educational issues in addition to the hearing loss, and also provide information to families about the chance that they could have additional children who are deaf or hard of hearing.
So when we think about hearing loss, we divide hearing loss into two broad categories, hearing loss that occurs by itself or isolated and a hearing loss that occurs with other medical concerns that we may call a syndrome. And a syndrome simply means a collection of features that has a common cause. If we believe a child or an individual has an isolated form of hearing loss, we typically offer a hearing loss panel.
The panel looks at a number of genes known to cause mostly the isolated forms of hearing loss and a few of the syndromic forms because a child may be too young for us to have noticed.
The other concerns that may co-occur if a child or an adult is thought to have more issues than just the hearing loss, the hearing loss panel probably is not the most appropriate test for them.
We typically start out testing by just evaluating the person who has hearing loss and if needed, we may need to get samples from other family members to help sort out the information. So this day we tend to have families receive a kit from a laboratory in the mail that they get a cheek swab from their child, send it back to the lab, and then it's processed for the results that we provide.
With an interpretation for children under a year of age, they may need to come in for a blood draw. So the process really starts though with an appointment. So we have individuals come in, see our otolaryngologist, ENT physician, meet with me as a genetic counselor and then talk with them in more, more detail about their family history, about their hearing history, and explain the genetic testing in more detail, the kind of results that we can get.
If an individual has hearing loss on both sides and their hearing loss was evident before they learned to speak, there is roughly a 40 to 60% likelihood that we will find a genetic explanation if an individual has asymmetric hearing loss. So the hearing does not seem to be the same on both sides, or is unilateral one-sided? The ability of our testing is less, but we would certainly go over those details with you before your decision.
In roughly 70% of the cases, we find that an individual has isolated hearing loss. About 30% of the time a person will have a syndromic form. So most times through our testing, we are not surprised. We find out a person has isolated hearing loss, but sometimes we are not expecting the results. And so family members may decide to get insurance in advance of the testing like life insurance, disability or long-term care before testing is completed.
What kinds of results can we get? We can get a result where the lab clearly identifies an alteration, and we know that is the cause of the hearing loss. On the other end of the spectrum, sometimes we are not able to find any alteration, or the alterations are known to not be associated with hearing loss. But sometimes we have alterations where the laboratory does not have enough data to say whether it causes hearing loss or not. And so we may be faced with time to have to wait for the laboratory to get more information.
The best way to start this process then is to schedule an appointment in our pediatric hearing clinic, and I would invite you if you have further questions before you schedule, you can reach out to me. My name again is Kristal, and my direct number is 5 3 1 3 5 5 6 3 6 5 or reach me by email Kristal, K-R-I-S-T-A-L dot Platt, P-L-A-T-T at Boys Town, B-O-Y-S-T-O-W-N.org.