Study: Stuttering Is (Often) In The Genes Researchers have found gene mutations for stuttering, an ancient and common disorder that often runs in families. Scientists and advocates say the discovery demonstrates that stuttering is often a biological condition — not caused by overbearing parents or a psychological disturbance.
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Study: Stuttering Is (Often) In The Genes

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Study: Stuttering Is (Often) In The Genes

Study: Stuttering Is (Often) In The Genes

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Researchers say they've found genes that cause stuttering. About three million Americans stutter. Though many overcome it or learn to live with it, it can cause enormous suffering and carry a social stigma. Scientists say the discovery marks the strongest link so far between genetic mutations and a behavioral problem. NPR's Richard Knox reports.

RICHARD KNOX: Jane Fraser wishes her father were alive to hear the news, that there's a genetic cause for stuttering. Malcolm Fraser was a successful businessman who struggled to speak his whole life, starting with his own name.

Ms. JANE FRASER (President, Stuttering Foundation of America): He had a great deal of difficult with that. He would go...

(Soundbite of stuttering noise)

Ms. FRASER: ...Fraser. And by the time he got his name out, he was just wrought up.

KNOX: He founded the Stuttering Foundation of America, which his daughter now heads.

Ms. FRASER: One of the things that always worried him was that he simply wasn't working hard enough. If he just tried harder, he could keep himself from stuttering.

KNOX: Humans have probably stuttered almost as long as they could speak. Dennis Drayna led the team that found the first genes for stuttering. Their discovery was just published online by the New England Journal of Medicine.

Dr. DENNIS DRAYNA (National Institute on Deafness and Other Communication Disorders): Stuttering, as a disorder, has been extremely well described since biblical times. There's an Egyptian hieroglyph for stuttering.

KNOX: Drayna says many people consider stuttering an emotional problem, rooted in the victim's upbringing.

Dr. DRAYNA: Bad parenting, you know, overanxious mothers, these sorts of things. And, of course, there was never whit of evidence to support these suggestions, but, you know, it's convenient to blame the parents, right?

KNOX: Drayna never believed this, because most of the time, stuttering runs in families. That points to genes. To find stuttering genes, Drayna and his colleagues started with a large Pakistani family. They zeroed in on a particular part of a certain chromosome. Eventually, they found a bunch of mutations strongly linked to stuttering. These mutations worked in the genes they expected.

Dr. DRAYNA: It was really quite a surprise.

KNOX: The stuttering mutations are in well-studied genes that control basic functions in all cells. When these so-called metabolic genes go wrong, really bad things can happen, fatal diseases like Tay-Sachs and Gaucher's Disease.

Dr. DRAYNA: So we thought, oh, it can't be this. In fact, it was this.

KNOX: He doesn't know why these stuttering mutations don't wreak more havoc. Maybe they just gum up the workings of specific cells in the brain that govern speech.

Dr. DRAYNA: We believe we will learn really a lot of important new things about the structures and functions inside the brain that give us the unique capability of speech.

KNOX: The finding may also lead to better therapies. If the stuttering mutation involves a missing or defective enzyme, for instance, maybe doctors will be able to replace it. The news that there is a genetic basis for much stuttering comes as a huge relief for people who stutter, like Kristin Chmela.

Ms. KRISTIN CHMELA: I have believed in my heart and in my body that stuttering has always had a neurophysiologic basis.

KNOX: Chmela has worked her whole life to overcome stuttering. Now she gives therapy to clients who stutter. She's sure they'll benefit from the discovery.

Ms. CHMELA: It's going to have a lot of implications, just psychologically, for a lot of clients who sometimes, you know, go to bed at night - I remember doing it as a teenager - and thinking, well, maybe tomorrow when I wake up, it will be gone. This is joy. It's joy.

KNOX: Happy to know at last that stuttering is not the fault of those who suffer from it.

Richard Knox, NPR News.

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