Difficulties in gene localization for Tourette's syndrome. Clinical aspects

Neuroreceptor subunit genes and the genetic susceptibility to Gilles de la Tourette syndrome

Segregation studies have shown that Gilles de la Tourette Syndrome (GTS) is probably transmitted as an autosomal dominant gene disorder and can therefore be studied by classical linkage analysis to identify susceptibility loci. Many neurotransmitter systems have been implicated in the etiology of GTS. Most recently the alpha-1 subunit of the glycine receptor etiologically responsible for hyperekplexia has been hypothesized as the cause of the susceptibility to GTS. Because of this and the high concentration of other neuroreceptor genes at 5q33-35, it was decided to study this region and the associated gene cluster on chromosome 4p12-16 in a large British kindred multiply affected with GTS and chronic motor tics. The genotypes of the microsatellite markers at these loci were determined by polymerase chain reaction. The allele data were analyzed using both parametric and nonparametric methods. Approximate multipoint maps were constructed across the regions of interest using FASTLINK. All of the lod scores produced were negative, showing no evidence of linkage to GTS in the family studied. The multipoint maps showed good exclusion across these regions. The glycine receptor gene responsible for hyperekplexia and the other neuroreceptor genes examined in this paper are not involved in the etiology of GTS in this large pedigree.

Tourette syndrome. Neuropsychological tests for obsessive-compulsive disorder and attention deficit hyperactivity disorder

Recent evidence has suggested that the commonly observed comorbid behavioral disorders of Tourette syndrome, including attention deficit hyperactivity disorder and obsessive-compulsive disorder clearly have an impact on cognitive, educational, and psychosocial function. These behavioral features of Tourette syndrome can be more debilitating than the cardinal motor features of the disorder and they require careful clinical assessment so that appropriate treatment intervention can be offered to patients and their families. This article focuses on objective neuropsychological and behavioral assessment of obsessive-compulsive disorder and attention deficit hyperactivity disorder which have proven useful for both the clinical evaluation and treatment of obsessive-compulsive disorder and attention deficit hyperactivity disorder associated with Tourette syndrome and in the research setting. Instruments with proven psychometric reliability and validity for assessing obsessive-compulsive disorder and attention deficit hyperactivity disorder which also have been useful in Tourette syndrome populations are discussed. Objective and quantitative assessment of these comorbid behavioral conditions greatly enhance our ability to treat the full neurobehavioral spectrum of Tourette syndrome.