NEW YORK - Why people stutter has long been a medical mystery, with the condition blamed over the years on emotional problems, overbearing parents and browbeating teachers. Now, for the first time, scientists have found genes that could explain some cases of stuttering.
"In terms of myth busters, this is really an important step forward," said Jane Fraser, president of the Stuttering Foundation.
Researchers taking part in a government-funded study discovered mutations in three genes that appear to cause the speech problem in some people. Stuttering tends to run in families, and previous research suggested a genetic connection. But until now, researchers had not been able to pinpoint any culprit genes.
Dennis Drayna, a geneticist and senior author of the study, said he hopes the results help convince doubters that stuttering "is almost certainly a biological problem."
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The research - released Wednesday by the New England Journal of Medicine - also points to a possible enzyme treatment for stuttering someday.
Without a known cause, stuttering has been attributed to such things as nervousness, lack of intelligence, stress or bad parenting.
The gene discovery should lift that guilt, she said.
Drayna and other experts said that while stress and anxiety can make stuttering worse, they do not cause it.
"It really is not an emotional disorder. It doesn't come from your interactions with other people," he said.
Stuttering usually starts in children as they are learning to talk. Most youngsters lose their stutter as their brain develops. For some, the stuttering persists. An estimated 3 million Americans stutter.
"This is a very difficult disorder to study," said Drayna, who is with the National Institute on Deafness and Other Communication Disorders.
To find the genes, Drayna and others first looked at a large, inbred Pakistani family with many members who stuttered, and discovered a mutation on Chromosome 12. Then they found the same mutation and two other mutated genes in a group of nearly 400 other people from Pakistan, the U.S. and England who stutter.
