The exact cause of Tourette's is unknown, but it is well established that both genetic and environmental factors are involved. The overwhelming majority of cases of Tourette's are inherited, although the exact mode of inheritance is not yet known, and no gene has been identified. Tics are believed to result from dysfunction in the thalamus, basal ganglia, and frontal cortex of the brain, involving abnormal activity of the brain chemical, or neurotransmitter, dopamine. In addition to dopamine, multiple neurotransmitters, like serotonin, GABA, glutamate, and histamine (H3-receptor), are involved.