Genetic Mutations Linked to Stuttering
Researchers Identify 3 Genes That May Play a Role in Stuttering
Feb. 10, 2010 -- Researchers with the National Institutes of Health (NIH)
have identified three genes that may predispose people to stuttering -- a
condition that affects 3 million Americans and 5% of young children.
Because stuttering tends to run in families, it has long been suspected that
genes play a role in the speech disorder.
In unique genetic research involving families with clusters of persistent
stutterers, investigators with the NIH's National Institute on Deafness and
Other Communication Disorders (NIDCD) identified a likely location of gene
variants associated with the disorder.
In their latest research, the researchers found specific gene mutations that
appear to lead to stuttering.
The findings appear today online in the New England Journal of
Jane Fraser, president of the support and education group Stuttering
Foundation of America, calls the identification of a genetic component
associated with the disorder a big step forward.
"For adults who stutter this is huge because it proves there is a biological
reason for stuttering," she tells WebMD. "So many people who stutter feel
extreme guilt and think that if they just tried harder they could get over
She adds that for many parents of children who stutter, the news will come
as a relief.
"Every day we get calls from parents asking what caused their child's
stuttering," she says. "What they are really asking is, 'Did I cause it?' We
can now say with a lot more assurance that the answer is no."
Normal speech involves a series of coordinated muscle movements associated
with breathing, voice production, and movement of the throat, palate, tongue,
and lips. These muscle movements are controlled by the brain and monitored
through the senses of hearing and touch.
This normal speech is disrupted in stutterers, but the cause of this
disruption has not been understood.
While stuttering affects all ages, it most often occurs in young children
who are still learning verbal communication.
Roughly one in 20 children has the condition. Young boys are twice as likely
to stutter as young girls; older boys are three to four times more likely to
stutter than older girls.
Most children eventually outgrow stuttering; about 1% of adults stutter.
Identifying Genetic Mutations
In the newly published study, NIDCD geneticist Dennis Drayna, PhD, and
colleagues built on earlier work involving 46 Pakistani families with large
numbers of persistent stutterers.
They identified mutations in a gene known as GNPTAB in the family members
who stuttered and looked for these gene mutations in 46 stutterers from the
original families and 77 Pakistani stutterers that were not members of these
The study also included close to 550 stutterers and non-stutterers living in
the United States and the U.K.
The GNPTAB mutations were present in many of the stutterers but in none of