While the heritability of acute RF has been estimated at 60%, few replicable genetic susceptibility loci have been identified (Engel et al. 2011). Other autoimmune disorders such as SLE have also been associated with increased rates of OCD (Bachen et al. 2009), and RA is associated with higher risk of concurrent mood and anxiety disorders (Nicassio 2010). Low but non-zero rates of SLE and type 1 diabetes were identified in the OCGAS cohort, both within the expected range. Higher-than-expected rates of RF—shared by first-degree relatives both with and without OCD—support the potential familial association suggested by preliminary studies. Further work that includes self-report data in healthy controls—and additional population-level epidemiological data—is needed to confirm and extend these findings. One limitation of existing national registries is the lack of detailed information on clinical phenotype, which may be relevant in understanding prognosis and response to conventional therapeutic agents in these individuals.
