In the present study, we analyzed the candidate gene SLC1A1, which encodes the neuronal glutamate transporter, in a large collection of OCD probands and controls in light of increasing interest in glutamatergic neurotransmission in OCD development and its treatment. We identified an SLC1A1 haplotype that was strongly associated with OCD that consists of 3 markers between intron 2 and the 3′ untranslated region of SLC1A1, 2 of which we found to be SNPs that predict gene expression levels (ie, eQTLs) in lymphoblastoid cell lines. In addition, another eQTL polymorphism, located somewhat upstream from SLC1A1, was strongly correlated with an OCD subphenotype (hoarding), as evaluated by 2 validated scales. Our data corroborate the hypothesis of dysfunctional glutamatergic neurotransmission in OCD and hoarding, mediated in part through SLC1A1.
