“The King’s Speech” Focuses Attention on Stuttering
Academy award-winner Colin Firth’s portrayal of King George VI in the recent hit movie “The King’s Speech” highlights the plight of more than 3 million Americans who suffer from stuttering. Stuttering affects nearly 60 million people worldwide, and boys are more than twice as likely as girls to stutter (National Institute of Health [NIH], 2010). The good news is that approximately 75 to 85 percent of those who stutter in childhood will outgrow it as adults. However, there is currently no way to predict who will be cured.
Traditionally, stuttering was believed to be caused by some emotional trauma in early childhood. This is termed psychogenic stuttering. Two other types of stuttering have also been described in the literature. Developmental stuttering is the most common form of stuttering, and occurs in young children while they are still learning speech and language skills. Scientists believe that developmental stuttering occurs when children’s speech and language abilities are unable to meet the child’s verbal demands. Neurogenic stuttering is another type of stuttering usually occurring after a stroke, head trauma, or other type of brain injury. In neurogenic stuttering, the brain has difficulty coordinating the different components involved in speaking because of signaling problems between the brain and nerves or muscles.
However, several years ago, researchers noted that stuttering tends to be familial, and began to suspect that there may be a genetic component to this disorder. In a recent research study by the NIH last year, researchers identified mutations in a gene known as GNPTAB in affected individuals. Together with two other proteins, GNPTG and NAGPA, GNPTAB is involved in cell metabolism. Researchers then discovered mutations in one or more of these three genes in people who stutter.
GNPTAB and GNPTG have previously been tied to metabolic diseases known as mucolipidosis, in which improperly recycled cell components accumulate in the lysosome (NIH, 2010). This disorder can ultimately lead to joint, skeletal, heart, liver and other health problems as well as developmental abnormalities in the brain.
The discovery of specific gene mutations as a potential cause of stuttering is ground-breaking news and may point the way to new approaches for treatment. Current treatments for some lysosome storage disorders involve injecting manufactured enzyme into a person's bloodstream to replace the missing enzyme (NIH, 2010). A similar approach might prove effective in treating some types of stuttering in the future.
For additional information, visit: http://www.nih.gov/researchmatters/march2010/03012010stutter.htm