The inheritance of Gilles de la Tourette's syndrome and associated behaviors. Evidence for autosomal dominant transmission

Area of Science:

• Genetics
• Neuroscience
• Psychiatry

Background:

• Gilles de la Tourette's syndrome (GTS) is a complex neurological disorder.
• Previous studies suggest chronic tics and obsessive-compulsive disorder (OCD) may be related to GTS.
• Understanding the genetic transmission of GTS is crucial for diagnosis and treatment.

Purpose of the Study:

• To investigate genetic hypotheses regarding the transmission mode of GTS.
• To analyze segregation patterns in families with GTS.
• To determine the etiological relationship between GTS, chronic tics, and OCD.

Main Methods:

• Segregation analysis was performed on 30 nuclear families with 27 index cases of GTS.
• Three diagnostic schemes were used to define affected family members.
• Penetrance estimates for genotypes (AA, Aa, aa) were calculated for males and females.

Main Results:

• High penetrance estimates were observed for genotypes AA and Aa in both sexes.
• Low penetrance was noted for genotype aa, particularly in females.
• Approximately 10% of patients were predicted to be phenocopies, suggesting non-genetic factors or incomplete penetrance.
• Obsessive-compulsive disorder was found to be etiologically related to GTS and chronic tics.

Conclusions:

• GTS is inherited as a highly penetrant, sex-influenced, autosomal dominant trait.
• Obsessive-compulsive disorder is etiologically linked to Tourette's syndrome and chronic tics.
• The findings support a shared genetic diathesis for these conditions.