A total-population multigenerational family clustering study of autoimmune diseases in obsessive-compulsive disorder and Tourette’s/chronic tic disorders

The association between obsessive-compulsive disorder (OCD) and Tourette's/chronic tic disorders (TD/CTD) with autoimmune diseases (ADs) is uncertain. In this nationwide study, we sought to clarify the patterns of comorbidity and familial clustering of a broad range of ADs in individuals with OCD, individuals with TD/CTD and their biological relatives. From a birth cohort of 7 465 455 individuals born in Sweden between 1940 and 2007, we identified 30 082 OCD and 7279 TD/CTD cases in the National Patient Register and followed them up to 31 December 2013. The risk of 40 ADs was evaluated in individuals with OCD, individuals with TD/CTD and their first- (siblings, mothers, fathers), second- (half siblings) and third-degree (cousins) relatives, compared with population controls. Individuals with OCD and TD/CTD had increased comorbidity with any AD (43% and 36%, respectively) and many individual ADs. The risk of any AD and several individual ADs was consistently higher among first-degree relatives than among second- and third-degree relatives of OCD and TD/CTD probands. The risk of ADs was very similar in mothers, fathers and siblings of OCD probands, whereas it tended to be higher in mothers and fathers of TD/CTD probands (compared with siblings). The results suggest a familial link between ADs in general (that is, not limited to Streptococcus-related conditions) and both OCD and TD/CTD. Additional mother-specific factors, such as the placental transmission of antibodies, cannot be fully ruled out, particularly in TD/CTD.grant from the Tourette Association of America (Mataix-Cols). Dr. Frans was supported by the Swedish Brain Foundation. Ms. Ana Pérez-Vigil was supported by a grant from the Alicia Koplowitz Foundation. Dr. Fernández de la Cruz is supported by a Junior Researcher grant from the Swedish Research Council for Health, Working Life and Welfare (FORTE grant number 2015-00569). Dr. Crowley was supported by NIMH grants R01MH105500 and R01MH110427. Dr. Rück was supported by a grant from the Swedish Research Council (K2013-61P-22168). We also acknowledge financial support from the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867. Dr. Lichtenstein is supported by grants from the Swedish Research Council for Health, Working Life and Welfare and the Swedish Research Council.Accepte