Given the hypothesis that Tourette and other tic disorders represent a phenotypic spectrum with a shared genetic etiology, Tourette PRS derived from the GWAS meta-analysis was compared in Tourette and tic spectrum cases in the Icelandic deCODE sample (Figure 2 and Figure S5). Tourette PRS was significantly higher in both deCODE Tourette syndrome cases and tic spectrum cases compared to controls (OR=1.33, p=5.3×10−9 and OR=1.20, p=5.2 ×10−4, respectively), explaining 0.78% and 0.42% of the phenotypic variance, respectively. Direct comparison between case groups confirmed that deCODE Tourette cases carried a higher Tourette syndrome polygenic burden than subjects with other tic spectrum disorders (OR=1.14, p=0.05), representing an excess 0.37% of the phenotypic variance (Figure 2).
