Genetic correlates in trichotillomania - A case-control association study in the South African Caucasian population

Background: Trichotillomania (TTM), a prevalent and disabling psychiatric disorder characterized by repetitive hair-pulling, is presently classified as an impulse control disorder (ICD). Some have argued, however, that TTM is an obsessive-compulsive spectrum disorder (OCSD). There is some evidence that both disorders (OCD and TTM) are mediated by serotonergic (5-HT) and dopaminergic pathways. Methods: The aim of the present investigation was to assess the role of candidate genes encoding components within the 5-HT and dopaminergic neurotransmitter pathways in mediating TTM. South African Caucasian TTM subjects (n=39), OCD (n=250) and control subjects (n=152) were genotyped for variants in 5-HT and dopaminergic candidate genes. Results: Both genotypic and allelic distributions of the 5-HT receptor 2A (5-HT_2A) T102C variant were found to be significantly different between the TTM and control subjects (p=0.028 and p=0.024, respectively), and a trend towards significance was noted between the TTM and OCD subjects (p=0.084 and p=0.080 for genotype and allele analyses, respectively), with the T102T-genotype found to confer susceptibility to the development of TTM. Conclusion: This investigation provides preliminary evidence for the involvement of 5-HT_2A in the molecular aetiology of TTM and supports the need for further replication in a larger dataset. The present data are consistent with previous findings that 5-HT_2A plays a role in mediating impulse dyscontrol.