Obsessive-compulsive disorder and the promoter region polymorphism (5-HTTLPR) in the serotonin transporter gene (SLC6A4): a negative association study in the Afrikaner population.

A polymorphism (5-HTTLPR) in the promoter region of the serotonin transporter gene (SLC6A4) has been reported to have functional significance and to be associated with obsessive-compulsive disorder (OCD). However, other studies have generated confounding results. A study was undertaken to re-evaluate this association in subjects drawn from the relatively genetically homogeneous Afrikaner population of South Africa. Fifty-four OCD patients of Afrikaner descent and 82 ethnically matched control individuals were phenotyped and genotyped. No significant association was found between the distribution of the 5-HTTLPR genotypes at the SLC6A4 locus and OCD. A similar result (p = 0.108) was generated when a meta-analysis of the 5-HTTLPR polymorphism, combining the current study with a previously reported Caucasian group, was performed; the meta-study comprised 129 OCD patients and 479 control individuals. However, both studies lacked power. Therefore, evidence that variation in SLC6A4 plays a significant role in the development of OCD in the population groups studied is inconclusive. Future association studies in Caucasian populations may extend the power of such meta-analyses and assist in delineating the role of SLC6A4 in OCD.