To date, only one Tourette GWAS has been published (9). Although no single nucleotide polymorphisms (SNPs) met criteria for genome-wide significance (p<5×10−8), in aggregate, the top SNPs (p-values <1×10−3) were enriched for expression quantitative trait loci (eQTLs) in frontal cortex and for methylation quantitative trait loci (mQTLs) in the cerebellum, indicating that a significant proportion of these variants have biological relevance to Tourette syndrome, and perhaps also to other tic disorders. However, as with other neuropsychiatric disorders, much larger sample sizes are needed to elucidate the disorder’s genetic underpinnings. Here, we report the results of a GWAS meta-analysis from the Psychiatric Genomics Consortium (PGC) Tourette Syndrome Workgroup in a sample that is nearly four times larger than the initial GWAS. We also probe aggregated Tourette syndrome polygenic risk to test two specific hypotheses: 1) whether Tourette and related tic disorders have an underlying shared genetic etiology; and 2) whether Tourette polygenic risk scores correlate with worst-ever tic severity and might represent a future potential predictor of disease severity.
