Evidence for potential relationship between SLC1A1 and a putative genetic linkage region on chromosome 14q to obsessive-compulsive disorder with compulsive hoarding

Obsessive-compulsive disorder (OCD) is likely a disorder involving complex genetic transmission. This suggests that multiple genetic and environmental factors are involved in its etiology. This is complicated further by the probability of genetic heterogeneity for this phenotype. In this report, we describe a preliminary approach to deal with both complexities. SLC1A1, a glutamate transporter gene on chromosome 9p, was originally proposed to be related to OCD based on two linkage studies, and subsequently association of OCD to the gene has been replicated. Additionally, genetic linkage to a subtype of OCD, compulsive hoarding, has been reported on chromosome 14q. We hypothesized that both genomic regions contribute to OCD in some instances. Using the analytic program GENEFINDER we found that conditioning linkage on chromosome 14q to a marker adjacent to SLC1A1, reduced the size of the linkage region on chromosome 14q and provided evidence for interaction between the regions on chromosomes 9p and 14q.