David Baxter PhD
Late Founder
Does Tourette’s Run in Families?
June 9, 2010
Dozens of readers had questions about Tourette’s syndrome, the odd and poorly understand disorder that causes uncontrollable tics and vocalizations, after the disorder was profiled in a recent Patient Voices series. Here, Dr. Robert A. King and Dr. James F. Leckman of Yale School of Medicine respond to readers wondering whether Tourette’s is inherited and how common the disorder is.
Is Tourette’s Inherited?
My daughter is engaged to someone with Tourette’s. I worry about their children inheriting Tourette’s. What is the likelihood of that occurring?
Anonymous, San Francisco
A. Dr. King and Dr. Leckman respond:
Tourette’s likely has genetic determinants, but they may vary from family to family. When a parent has Tourette’s, sons have a higher risk of inheriting the condition than daughters. On average, about 20 percent of male offspring will have Tourette’s, compared to only about 5 percent of female offspring. The rates for a chronic motor tic disorder are a bit higher: 30 percent of the sons and about 9 percent of the daughters will have such a condition. In contrast, the rates are reversed for obsessive-compulsive disorder, or O.C.D., which sometimes accompanies Tourette’s, with 7 percent of sons and 15 percent of daughters developing symptoms of O.C.D. These are all approximate figures.
Over all, the total risk of inheriting Tourette’s syndrome, chronic tics or O.C.D. when one or both parents has one or more of these conditions is about 56 percent for sons and 30 percent for daughters.
That said, these figures come from research studies in which family members were very carefully interviewed about symptoms. Hence, some of these cases might not have been bothersome enough that they would ever have led to a medical visit. In reality, symptom severity can vary tremendously in affected individuals in a family, with many cases of Tourette’s, chronic tics, or O.C.D. being relatively mild or and not impairing everyday functioning.
A brochure on the genetics of Tourette’s is available for a modest fee at the Tourette’s Syndrome Association Web site.
How Common Is Tourette’s?
I think people would be surprised at how many have some form of Tourette’s. Most of them are mild, but it is a lot more widespread than most, including the medical community, care to admit.
Alex, New York City
A. Dr. King and Dr. Leckman respond:
Dear Alex, you are correct that tic disorders are relatively common. Last year, the Centers for Disease Control and Prevention reported the results of a nationwide telephone survey of households in the United States. They found that the prevalence of Tourette’s, as reported by parents, was 3 cases per 1,000 children, which works out to about 148,000 children nationwide.
The survey did not ask parents about chronic motor or vocal tics, which are much more common than Tourete’s itself. For example, a study of school-age children in Sweden found that Tourette’s was present in 6 per 1,000 children. Chronic motor tics were present in another 8 per 1,000 children, and another 5 per 1,000 children had chronic vocal tics. The most common condition was transient tics, which were observed in 48 per 1,000 children. The total for any tic disorder was 65 per 1,000, or 6.5 percent of all children.
June 9, 2010
Dozens of readers had questions about Tourette’s syndrome, the odd and poorly understand disorder that causes uncontrollable tics and vocalizations, after the disorder was profiled in a recent Patient Voices series. Here, Dr. Robert A. King and Dr. James F. Leckman of Yale School of Medicine respond to readers wondering whether Tourette’s is inherited and how common the disorder is.
Is Tourette’s Inherited?
My daughter is engaged to someone with Tourette’s. I worry about their children inheriting Tourette’s. What is the likelihood of that occurring?
Anonymous, San Francisco
A. Dr. King and Dr. Leckman respond:
Tourette’s likely has genetic determinants, but they may vary from family to family. When a parent has Tourette’s, sons have a higher risk of inheriting the condition than daughters. On average, about 20 percent of male offspring will have Tourette’s, compared to only about 5 percent of female offspring. The rates for a chronic motor tic disorder are a bit higher: 30 percent of the sons and about 9 percent of the daughters will have such a condition. In contrast, the rates are reversed for obsessive-compulsive disorder, or O.C.D., which sometimes accompanies Tourette’s, with 7 percent of sons and 15 percent of daughters developing symptoms of O.C.D. These are all approximate figures.
Over all, the total risk of inheriting Tourette’s syndrome, chronic tics or O.C.D. when one or both parents has one or more of these conditions is about 56 percent for sons and 30 percent for daughters.
That said, these figures come from research studies in which family members were very carefully interviewed about symptoms. Hence, some of these cases might not have been bothersome enough that they would ever have led to a medical visit. In reality, symptom severity can vary tremendously in affected individuals in a family, with many cases of Tourette’s, chronic tics, or O.C.D. being relatively mild or and not impairing everyday functioning.
A brochure on the genetics of Tourette’s is available for a modest fee at the Tourette’s Syndrome Association Web site.
How Common Is Tourette’s?
I think people would be surprised at how many have some form of Tourette’s. Most of them are mild, but it is a lot more widespread than most, including the medical community, care to admit.
Alex, New York City
A. Dr. King and Dr. Leckman respond:
Dear Alex, you are correct that tic disorders are relatively common. Last year, the Centers for Disease Control and Prevention reported the results of a nationwide telephone survey of households in the United States. They found that the prevalence of Tourette’s, as reported by parents, was 3 cases per 1,000 children, which works out to about 148,000 children nationwide.
The survey did not ask parents about chronic motor or vocal tics, which are much more common than Tourete’s itself. For example, a study of school-age children in Sweden found that Tourette’s was present in 6 per 1,000 children. Chronic motor tics were present in another 8 per 1,000 children, and another 5 per 1,000 children had chronic vocal tics. The most common condition was transient tics, which were observed in 48 per 1,000 children. The total for any tic disorder was 65 per 1,000, or 6.5 percent of all children.
