Association between a catechol-o-methyltransferase polymorphism and obsessive–compulsive disorder in the Afrikaner population

Background: It has been proposed that the catechol-o-methyl transferase gene (COMT) may play a role in the pathogenesis of obsessive–compulsive disorder (OCD). Whereas studies in a North American population showed that the low activity (L) allele of a functional polymorphism in COMT was associated with OCD in male patients, this result was not supported by studies in a Japanese population. The present association study assessed the risk for OCD conferred by this COMT polymorphism in a geographically different patient group, namely, the relatively genetically homogeneous Afrikaner population of South Africa. Methods: Fifty-four unrelated OCD patients and fifty-four sex-matched controls were recruited from the same Afrikaner community. Patients and controls were phenotyped (DSM-IV) and genotyped for a NlaIII polymorphism with H (high activity) or L (low activity) alleles in the COMT gene. Results: The H/L genotype was significantly more common than expected in the OCD patient group (P=0.0017). Limitations: Replication studies with related individuals may be useful in discovering factors underpinning the H/L genotype abundance in the Afrikaner population. Conclusions: These results emphasise the need for further studies in genetically homogeneous populations to help define the complex etiology of this disease.