Association studies of the 5-HT2A T102C and the 5-HT2C Cys23Ser receptor gene polymorphisms and suicidal behaviour

Disruption of the serotonergic system is suggested to be involved in suicidal behaviour and depression. Results from polymorphism studies have been equivocal in their appraisal of a genetic contribution to this involvement. In the current investigation, the frequencies of the 5-HT2A receptor (T102C) and 5-HT2C receptor (Cys23Ser) polymorphisms were examined in a well-characterised sample of deliberate self-harm (DSH) patients and in healthy controls. DSH patients (n= 144) were recruited from the general hospital in Oxford (UK) as part of the WHO/EURO multicentre study on parasuicide. Interviews were conducted using the European Parasuicide Interview Schedule. Additional psychiatric and personality assessments were carried out using structured interview schedules. Controls (currently n = 265; matched for age, gender and ethnicity) were recruited from local blood donation clinics. Genotyping was performed using PCR-based methods (Marshall et al., 1999. Am J Med Genet. 88; 621-7). Allele frequencies were in Hardy-Weinberg equilibrium. Preliminary Chi-squared (cs) analysis of the 5-HT2A (T102 vs. C102: cs = 0.0) and 5-HT2C (Cys23 vs. Ser23: males-cs = 0.38; females-cs = 0.64) revealed no association between allele frequencies and DSH. Within the DSH group there was no association of allele frequencies with either history of major depression or with a composite score for high suicide risk. These results indicate a lack of association between these polymorphisms and suicidal behaviour.