The genetics and phenotypes of Gilles de la Tourette syndrome are complicated. Once indicated to be inherited as a single major autosomal dominant condition, several areas of interest on many chromosomes and one gene have been identified for Gilles de la Tourette syndrome, but no results have been replicated. Factor analytic studies suggest that there are more than one Gilles de la Tourette syndrome phenotype and it is not a unitary condition.
To characterize Gilles de la Tourette syndrome phenotypes in a group of individuals who underwent a complete genome scan.
We studied 85 members of a multiply affected multigenerational kindred, of whom 69 displayed Gilles de la Tourette syndrome-related symptoms (tics, obsessive-compulsive behaviours, obsessive-compulsive symptoms, attention deficit hyperactivity symptoms), using first a hierarchical cluster analysis followed by a principal component factor analysis.
Three significant factors resulted from our analysis, accounting for approximately 42% of the symptomatic variance: Factor 1 (predominantly 'pure tics'), Factor 2 (predominantly 'attention deficit hyperactivity disorder and aggressive behaviours') and Factor 3 (predominantly 'depression-anxiety-obsessional symptoms and self-injurious behaviours'). Different kinds of tics occurred in all three factors. Only frowning/raising eyebrows and sniffing/smelling loaded significantly on both Factors 1 and 3.
Our results give further evidence that the genetics of Gilles de la Tourette syndrome is complex and suggest that Gilles de la Tourette syndrome is not a unitary condition, thus confirming the results of earlier studies which have described several Gilles de la Tourette syndrome phenotypes. Although a genome scan on the pedigree reported three areas of interest and the present study found three factors, further studies would have to be undertaken to elucidate whether the three factors 'mapped' with the genetic data. Possible reasons for our findings and suggestions for future research are discussed.
"Thus, given the number of comorbidities and the complexity of the phenomenology of tics and tic -related behaviors (Lewis and Kim, 2009; Worbe et al., 2010b) GTS is a prototype of a complex neuropsychiatric spectrum disorder (Cavanna et al., 2009; Robertson, 2011; Roessner et al., 2005, 2007; Wanderer et al., 2012). Using principal component factor and hierarchical cluster analyses different GTS-subtypes have been postulated (Alsobrook and Pauls, 2002; Cavanna et al., 2011; Mathews et al., 2007; Robertson and Cavanna, 2007). Although variations exist between the reported results, depending on the exact factor loadings or the identified clusters, it has become clear that core features of GTS include simple and complex tics, impulsivity , aggressive (self-injurious behavior, coprophenomena) and compulsive (or repetitive) behaviors (Alsobrook and Pauls, 2002; Cavanna et al., 2011; Mathews et al., 2007; Robertson, 2011). "
[Show abstract][Hide abstract] ABSTRACT: Gilles de la Tourette syndrome (GTS) holds a prime position as a disorder transgressing the brittle boundaries of neurology and psychiatry with an entangling web of motor and behavioural problems. With tics as the disorder's hallmark and myriads of related signs such as echo-, pali- and coprophenomena, paralleled by a broad neuropsychiatric spectrum of comorbidities encompassing attention deficit hyperactivity disorder, obsessive-compulsive disorder but also self-injurious behaviour and depression, GTS pathophysiology remains enigmatic. In this review, in the light of GTS phenomenology, we will focus on current theories of tic-emergence related to aberrant activity in the basal ganglia and abnormal basal ganglia - cortex interplay through cortico-striato-thalamocortical loops from an anatomical, neurophysiological and functional-neuroimaging perspective. We will attempt a holistic view to the countless major and minor drawbacks of the GTS brain and comment on future directions of neuroscientific research to elucidate this common and complex neuropsychiatric syndrome, which merits scientific understanding and social acceptance.
"As these results were based on lifetime rather than current tic symptomatology, participant data may have been biased by limits in retrospective self-report, and tics forming the clusters may not have been concurrently present. Robertson and Cavanna (2007) also studied child and adult participants, 69 of whom exhibited tic and related symptoms using the National Hospital Interview Schedule for Gilles de la Tourette Syndrome (NHIS-GTS; Robertson and Eapen 1996), although they did not necessarily meet criteria for a tic disorder. Additionally, several of the items included non-tic-specific phenomena (e.g., " anxiety " ). "
[Show abstract][Hide abstract] ABSTRACT: Tic disorders are heterogeneous, with symptoms varying widely both within and across patients. Exploration of symptom clusters may aid in the identification of symptom dimensions of empirical and treatment import. This article presents the results of two studies investigating tic symptom clusters using a sample of 99 youth (M age = 10.7, 81% male, 77% Caucasian) diagnosed with a primary tic disorder (Tourette's disorder or chronic tic disorder), across two university-based outpatient clinics specializing in tic and related disorders. In Study 1, a cluster analysis of the Yale Global Tic Severity Scale (YGTSS) identified four symptom dimensions: predominantly complex tics; simple head/face tics; simple body tics; and simple vocal/facial tics. In Study 2, these clusters were shown to be differentially associated with demographic and clinical characteristics. Findings lend support to prior research on tic phenomenology, help to organize treatment goals, and suggest symptom dimensions of tic disorders for further evaluation.
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