Tryptophan hydroxylase-1 gene variants associate with a group of suicidal borderline women.
Alterations in the serotonin (5-HT) system have been related to impulsive aggression and suicidal behavior, common features of the borderline personality disorder (BPD). Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in 5-HT biosynthesis. Two isoforms are known, TPH-1 and TPH-2. TPH-1 has been correlated to various psychiatric and behavioral disorders by gene polymorphism association studies. We aimed to determine whether specific TPH-1 haplotypes associate with BPD. A case-control design was employed. The control group included 98 women without psychiatric history. In all, 95 patients were included, all Caucasian women with a BPD diagnosis who had attempted suicide at least twice during their lifetime. Exclusion criteria were: (i) substance dependence; (ii) dementia or other irreversible organic brain syndromes; (iii) psychotic disorders or major depressive illness with melancholic features; (iv) life-threatening eating disorders. Six single-nucleotide polymorphisms (SNPs) were found at significant linkage disequilibrium across 23 kb of the TPH-1 gene in both patients and controls, suggesting a haplotype block structure. While no individual SNP showed association, several haplotypes associated with the BPD group. In particular, one six-SNP haplotype was absent from the control group while representing about one-quarter of all haplotypes in the BPD group (corrected P<<10(-5)). A 'sliding window' analysis attributed the strongest disease association to haplotype configurations located between the gene promoter and intron 3. We conclude that TPH-1 associates with BPD in suicidal women. Our data support the expectation that haplotype analysis is superior to single locus analysis in gene-disease, case-control association studies.
Psychiatry Section, Department of Clinical Neuroscience, Karolinska Institute and Hospital, Stockholm, Sweden. ghazal.zaboli@ki.se
Ghazal
G
Zaboli
Rinat
R
Gizatullin
Asa
A
Nilsonne
Alexander
A
Wilczek
Erik G
EG
Jönsson
Ewa
E
Ahnemark
Marie
M
Asberg
Rosario
R
Leopardi
D000328:Adult; D000483:Alleles; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012306:Risk; D013405:Suicide / Q000523:psychology*; D014365:Tryptophan Hydroxylase / Q000235:genetics*
D014365:Tryptophan Hydroxylase