Future molecular genetic studies should focus on collection of DNA from large numbers of OCD and TD/CTD cases with rich clinical and environmental risk factor information (e.g., personal and family history of AD, documented temporality between infection and symptom onset). At least one study of this type is currently ongoing in TD/CTD.39, 40 In addition, comparison of genetic markers in patients with vs without additional neurological or immunological symptoms (PANS [Pediatric Acute-onset Neuropsychiatric Syndrome]/PANDAS) may yield mechanistic insight. Given the complexity of these psychiatric and immunological traits, well-powered analyses are key to robust findings. An excellent demonstration of this comes from a recent analysis41 of GWAS data for more than 60,000 cases and controls representing three adult psychiatric disorders: schizophrenia, major depression, and bipolar disorder. The authors searched for biological pathways enriched for psychiatric risk variants and found that multiple immune signaling pathways were among the most robustly associated, providing a mechanistically-informative link between genetic and epidemiological studies for these disorders.
