Association analysis between gene variants of the tyrosine hydroxylase and the serotonin transporter in borderline personality disorder

Abstract

objectives. For patients with borderline personality disorder (BPD), we previously reported an independent effect of the catechol-o-methyl-transferase (COMT) low-activity (Met158) allele and an interaction with the low-expression allele of the deletion/insertion (short/long or S/L, resp.) polymorphism in the serotonin transporter-linked promoter region (5-HTTLPR). The purpose of the present study was to extend these findings to the tyrosine hydroxylase (TH) Val81Met single nucleotide polymorphism (SNP), the 5-HTTLPR S/L polymorphism incorporating the recently described functional A/G SNP within the long allele of the 5-HTTLPR (rs25531) as well as the variable number of tandem repeat (VNTR) polymorphism within intron 2 of the serotonin transporter gene (STin2). Methods. In 156 Caucasian BPD patients and 152 healthy controls, we tested for association between BPD and the TH Val81Met SNP, the 5-HTTLPR/rs25531 polymorphism, the STin2, the interaction of the TH Val81Met SNP with the tri-allelic 5-HTTLPR/rs25531, the interaction of the TH Val81Met SNP with STin2. Results. Between BPD patients and controls, we observed a slight over-representation of the TH Met81Met genotype in BPD patients compared to controls, but no statistically significant differences in genotype distribution of the individual markers after adjusting for multiple testing. Logistic regression analysis showed a lack of interaction between the TH Val81Met and the 5-HTTLPR/rs25531 as well as between the TH Val81Met and the STin2 polymorphism. Conclusions. These data do not suggest independent or interactive effects of the TH Val81Met, the 5-HTTLPR/rs25531, or the STin2 polymorphisms in BPD.