Causes
Tourette's syndrome is genetically inherited as a dominant trait. We
all inherit one set of genes from each parent. Many inherited genes only manifest
themselves if both sets carry the gene for that disease. Dominant genes like
Tourette's syndrome only require one copy - if either parent has the gene that
causes Tourette's syndrome, each child has up to a 50% chance of having the
disorder. However, the child isn't destined to have Tourette's syndrome, because
other genetic and environmental factors also play important roles. Boys born
to a parent with Tourette's syndrome are very likely to have the condition,
yet girls often don't. The girls, however, are likely to suffer from obsessive-compulsive
disorder. The gene(s) responsible for this syndrome is (are) not yet known.
Obsessive-compulsive behavior and attention deficit hyperactivity disorder
(ADHD) are very common in people with Tourette's syndrome, and may cause bigger
problems than the tics. ADHD is characterized by poor attention span and
impulsive behavior, while OCD involves repetitive carrying out of the same
task. In adults, this often involves habits like continually checking that the
door is locked or that the oven is turned off, or endless hand washing. A typical
obsessive-compulsive behavior in children is touching something with one hand,
then feeling you must "even things out" by touching it with the other.