The association between catechol-O-methyl-transferase Val 108/158Met polymorphism and suicide

Abstract

One of the candidate genes for suicide is also a gene in the pathway for catecholamine degradation encoding an enzyme catechol-O-methyl-transferase (COMT). It harbors a common functional polymorphism, a G to A nucleotide transition resulting in amino acid substitution from valine (Val) to methionine (Met) at position 158 (COMT Val 108/158Met; rs4680), that has been associated with psychiatric disorders characterized with an increased risk of suicidal behavior. We have performed the first study on Caucasian population examining the association between completed suicide and the COMT Val 108/158Met polymorphism. The study population consisted of 356 suicide victims and 198 control subjects. Significant difference in COMT Val 108/158Met variants' (genotypes, alleles and Val carriers) distribution was found only in male groups, between controls and suicide victims (P = 0.018, P = 0.031, P = 0.005), and between controls and violent suicide victims (P = 0.026, P = 0.042, P = 0.010). The r value from the standardized residuals showed that the Met/Met genotype (r = 2.03) in the control group contributed to these significant differences. In contrast to male subjects, no significant differences in the frequency of the COMT Val 108/158Met variants were detected between female control and female suicide groups; however, the power of calculation (range 0.161-0.680) was below the desired 0.800. In addition, the logistic regression analysis confirmed these significant differences. In conclusion, our results showed the overpresentation of the Met/Met genotype in male control subjects compared with male suicide victims, suggesting that this genotype of the COMT Val 108/158Met might be a protective factor against suicide. © 2011 The Authors. Genes, Brain and Behavior © 2011 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.