Archival ReportLatent Class Analysis of Gilles de la Tourette Syndrome Using Comorbidities: Clinical and Genetic Implications
Section snippets
Sample
The sample consisted of 952 individuals from 222 GTS families collected by the Tourette Syndrome Association International Consortium on Genetics (TSAICG) for affected sibling pair (ASP) genetic linkage studies (18, 19). Families were ascertained on the basis of presence of GTS in at least two siblings and the availability of at least one parent. Families were excluded if the proband had mental retardation or a pervasive developmental disorder or where both parents had a known diagnosis of GTS,
Sample Characteristics
From this sib-pair GTS sample, most affecteds (n = 668) had GTS diagnoses (n = 596), and a minority had CT diagnoses (n = 72). Subjects with GTS had a younger age at onset of tics and more frequent comorbid OCD and ADHD diagnoses compared with subjects with CT (Table 1).
Considering only GTS subjects, 75% had either OCD or ADHD, with approximately a third of the sample having both OCD and ADHD. The other third had comorbid OCD only, and a smaller subset (10%) had comorbid ADHD only (Figure 1).
Latent Class Analyses
Discussion
This study represents the first latent class analysis of GTS and its most common comorbidities, OCD and ADHD. We identified three GTS-affected classes, corresponding to GTS + OCS/OCB (Class III; n = 107), GTS + OCD (Class IV; n = 300), and GTS + OCD + ADHD (Class V; n = 229). Two additional classes were also identified in the larger family sample: minimal disorder (Class I; n = 281) and chronic tics (Class II; n = 35). We are confident that the LCA classes derived from these analyses are
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