Dennis Drayna, Ph.D., researcher for the National Institute on Deafness and Other Communication Disorders, answers questions from students at Glendale American Elementary School.
Dr. Drayna: Thank you for your interest in our research on stuttering. I’m happy to answer your questions as follows:
Claire: Why is it important to learn about this gene?
Dr. Drayna: The reason we're interested in learning about this gene is that this is a way to help us understand the causes of stuttering. Once we know what genes are altered in stuttering, we can see what kinds of proteins those genes make, and how and what they do in the body. This can tell us things that were previously unknown about stuttering.
Cynthia: Can people stop stuttering forever?
Dr. Drayna: Many people stop stuttering forever. Stuttering typically starts in young children who are 3 or 4 years old. Most of these children, about 75-80 percent, get over stuttering naturally, and never stutter again. In the rest of those children, stuttering can go on for years, sometimes for their whole life. But even for these people, speech therapy can be a big help, and sometimes it can help them stop stuttering forever.
Sedona: Why do you care about stuttering?
Dr. Drayna: Before I started to work on stuttering I didn't understand this disorder very well. I thought it was just a small annoying thing in a few people’s lives. However, then I learned that stuttering makes some people's lives miserable. Imagine if you knew exactly what you wanted to say but you couldn't say it, and then to make matters worse, people laughed at you because of it. The ability to talk to other people is one of the most important things in our life. Because it can ruin a person's ability to talk, stuttering can have a very bad impact on people, and our job at the National Institutes of Health is to perform research to solve such problems.
Eric: Why do people stutter?
Dr. Drayna: About half of people with lifelong stuttering do so because of something they inherit. The other half of stuttering has no cause that is obvious to us at this time.
Ciara: Why is it that the heritability of stuttering is high for twins?
Dr. Drayna: Scientists study twins because twins can help tell us how much of a disorder is due to genes and how much is due to other things, like diet or other environmental things. This is sometimes called the “nature versus nurture” question. Identical twins share all their genes, while fraternal twins share half their genes. So for example, if a disorder is 100 percent genetic in origin, identical twins will always both have that disorder, while fraternal twins will both have it in only 50 percent of the time. If one identical twin has a disorder and his or her identical twin does not have it, that disorder cannot be caused by genes alone. Twin studies tell us that stuttering is in the range of 50 to 70 percent genetic in origin.
Shantell: How are you going to find a cure for this disorder and not cause damage?
Dr. Drayna: Finding the cause of a disorder is the first step in making a cure for that disorder. Imagine trying to stop influenza if we didn't know what caused it. For thousands of years, people tried all sorts of things to prevent getting influenza. None of them worked, until we discovered that influenza is caused by a virus that we could grow in the laboratory. That enabled us to make a vaccine, and now we can prevent influenza with a flu shot. It can take many years to go from the discovery of the cause of a disorder to having a cure for it. Since no one knew any of the causes of stuttering previously, our finding of genes that cause stuttering is an important first step in developing a cure.
Missy: What percentage of Americans have problems with stuttering?
Dr. Drayna: About 5 percent of people stutter as young children. About 80 percent of these people get over stuttering, leaving about 1 percent of people who stutter in the general population. This is about 3 million people in the U.S. and about 60 million worldwide.
Asia: Is stuttering only inherited or can it be acquired as well?
Dr. Drayna: Stuttering can be acquired beyond young childhood. This happens when people have specific injuries to parts of their brain. This so-called acquired stuttering is rare. As one final note, when you're talking with a person who stutters, don't tell them to relax or slow down, and don't try to finish their sentences for them. This doesn't help them talk, and it can make their stuttering even worse. Just be patient and give them a chance to say what they want to say.
Dennis Drayna, Ph.D.
-From the Winter 2011 Newsletter