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Tourette syndrome is a neurodevelopmental disorder characterized by multiple motor and vocal tics, and the disorder is often accompanied by comorbidities such as attention-deficit hyperactivity-disorder and obsessive compulsive disorder. Tourette syndrome has a complex etiology, but the underlying environmental and genetic factors are largely unknown. IMMP2L (inner mitochondrial membrane peptidase, subunit 2) located on chromosome 7q31 is one of the genes suggested as a susceptibility factor in disease pathogenesis. Through screening of a Danish cohort comprising 188 unrelated Tourette syndrome patients for copy number variations, we identified seven patients with intragenic IMMP2L deletions (3.7%), and this frequency was significantly higher (P=0.0447) compared with a Danish control cohort (0.9%). Four of the seven deletions identified did not include any known exons of IMMP2L, but were within intron 3. These deletions were found to affect a shorter IMMP2L mRNA species with two alternative 5'-exons (one including the ATG start codon). We showed that both transcripts (long and short) were expressed in several brain regions, with a particularly high expression in cerebellum and hippocampus. The current findings give further evidence for the role of IMMP2L as a susceptibility factor in Tourette syndrome and suggest that intronic changes in disease susceptibility genes should be investigated further for presence of alternatively spliced exons.

Tourette syndrome (TS) is a childhood-onset complex neurobiological disorder characterized by a combination of persistent motor and vocal tics and frequent presence of other neuropsychiatric comorbidities. TS shares the fate of other complex disorders, where the genetic etiology is largely unknown, and identification of susceptibility genes through linkage and association studies has been complicated due to inherent difficulties such as no clear mode of inheritance, genetic heterogeneity, and apparently incomplete penetrance. Positional cloning through mapping of disease-related chromosome rearrangements has been an efficient tool for the cloning of disease genes in several Mendelian disorders and in a number of complex disorders. Through cytogenetic investigation of 205 TS patients, we identified three possibly disease-associated chromosome rearrangements rendering this approach relevant in chasing TS susceptibility genes.

Tourette syndrome (TS) is a chronic, neurobiological disease, characterized by the presence of motor and vocal tics and it is often accompanied by associated symptoms. The two best-known co-morbidities are Obsessive-Compulsive Disorder (OCD) and Attention Deficit Hyperactivity Disorder (ADHD). The fact that TS aggregates strongly in families suggests that family members share either genetic and/or environmental risk factors contributing to TS. Numerous studies have been performed to examine the familiality in TS, but clear-cut factors to predict hereditability in TS have not been found yet. We have examined a large Danish clinical cohort of children with TS (N=307). Validated diagnostic instruments were used to assess the presence of co-morbidities in the children with TS. A three-generation pedigree was drawn for all the probands and through reports from the family, a family history and the frequency of affected relatives was noted. The rates of tics, symptoms of OCD, and ADHD among relatives are similar to the rates found in other countries and are higher than in the general population. Although the role of sex in determining the phenotype has to be examined more thoroughly, we found that male relatives were more likely to have tics and female relatives were more likely to have symptoms of OCD. When comparing the relatives to male patients with relatives to female patients, there were no differences in the rates of symptoms, apart from symptoms of ADHD that were more frequent in second-degree relatives to female patients. The severity of tics and the presence of co-morbidity did not seem to predict the familiality of TS and its associated symptoms., (Copyright 2010 Elsevier Masson SAS. All rights reserved.)

Tourette syndrome (TS) is characterized by the presence of motor and vocal tics and is often accompanied by comorbid symptoms. We assessed the frequency of the comorbid symptoms obsessive-compulsive disorder obsessive-compulsive disorder, attention-deficit hyperactivity disorder (ADHD), rage attacks, sleeping disturbances, and depressive symptoms in a Danish clinical cohort of 314 children with TS using validated diagnostic instruments. For the assessment of symptoms of seasonal affective disorder and stuttering, we used a nonvalidated systematic interview. In total, only 10.2% of the children did not have any comorbid symptoms at all. If ADHD and/or obsessive-compulsive disorder were present, the rates of the comorbidities rage, symptoms of seasonal affective disorder, sleep disturbances, and depressive symptoms were significantly higher than if ADHD and/or obsessive-compulsive disorder were absent. The most severe tics were found in the group for which both ADHD and obsessive-compulsive disorder were present. Furthermore, there was a tendency toward more severe tics if other comorbid symptoms were present.