A haplotype containing quantitative trait loci for SLC1A1 gene expression and its association with obsessive-compulsive disorder.

Context: Recent evidence from linkage analyses and follow-up candidate gene studies supports the involvement of SLC1A1, which encodes the neuronal glutamate transporter, in the development of obsessive-compulsive disorder (OCD).

Objectives: To determine the role of genetic variation of SLC1A1 in OCD in a large case-control study and to better understand how SLC1A1 variation affects functionality.

Design: A case-control study.

A novel, putative gain-of-function haplotype at SLC6A4 associates with obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) is a disabling neuropsychiatric illness with strong segregation data indicative of major genetic contributions. Association analyses of common functional variants of the serotonin transporter gene (SLC6A4), a long-standing OCD candidate, have so far been inconsistent. Here, we set out to investigate the role of additional functional SLC6A4 loci in OCD.

A large case-control study of common functional SLC6A4 and BDNF variants in obsessive-compulsive disorder.

Both serotonin transporter (SLC6A4) and brain-derived neurotrophic factor (BDNF) genes have shown positive associations with obsessive-compulsive disorder (OCD) and some other psychiatric disorders, but these results have not been consistently replicated. To explore the hypothesis that this variability might result from the effects of differing combinations of overlooked variants within SLC6A4 together with small OCD and control sample sizes, we studied three common functional polymorphisms (5-HTTLPR, STin2, and the newly discovered SNP, rs25531) in the largest sample size of OCD patients (N=347) and controls (N=749) ever investigated. During methods development, we found evidence for potential SLC6A4 genotyping problems with earlier methodology, a third possible contributor to variability in earlier studies.