Previous studies have implicated frequent infections, low immunoglobulin titers, and higher rates of atopy among OCD probands together with increased prevalence of autoimmune diseases among their mothers (Murphy et al. 2010; Stagi et al. 2014; Yuce et al. 2014; Frankovich et al. 2015; Calaprice et al. 2017) (Supplementary Table S1). However, these reports are limited by the absence of control or population data, measurement of hematologic parameters only in the setting of acute symptom flares, restriction to PANS or PANDAS subtypes rather than heterogeneous or adult OCD samples, or small sample sizes. This study examined the prevalence of self-reported immune-mediated illnesses in patients with childhood-onset OCD not selected for PANDAS or PANS and compared these with expected ranges derived from a review of published population estimates. We hypothesized that shared genetic and environmental predisposing factors may contribute to increased rates of immune-related diseases among heterogeneous patients with childhood-onset OCD.
