While the underlying pathophysiological mechanisms remain to be elucidated, meta-analyses of family studies suggest heritability may be as high as 50%–60% in childhood-onset OCD (Nestadt et al. 2000; Mataix-Cols et al. 2013). Genetic association studies have implicated single nucleotide polymorphisms in genes involved in glutaminergic transmission as well as immune function (den Braber et al. 2016), although none has yet reached genome-wide significance (Stewart et al. 2013; Taylor 2013; Mattheisen et al. 2015; International Obsessive Compulsive Disorder Foundation Genetics Collaborative [IOCDF-GC] and OCD Collaborative Genetics Association Studies [OCGAS] 2018).
