Deliberate self-harm is associated with allelic variation in the tryptophan hydroxylase gene (TPH A779C), but not with polymorphisms in five other serotonergic genes

• Published in: Psychological medicine Vol. 33; no. 5; pp. 775 - 783
• Main Authors: POOLEY, E. C., HOUSTON, K., HAWTON, K., HARRISON, P. J.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.07.2003
• Subjects: Adult; Adult and adolescent clinical studies; Aged; Alleles; Biological and medical sciences; Carrier Proteins - genetics; Carrier Proteins - metabolism; Case-Control Studies; Female; Genetic susceptibility; Humans; Male; Medical sciences; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Membrane Transport Proteins; Middle Aged; Monoamine Oxidase - genetics; Monoamine Oxidase - metabolism; Nerve Tissue Proteins; Parasuicide; Polymorphism, Genetic; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Receptor, Serotonin, 5-HT2C; Receptors, Serotonin - genetics; Receptors, Serotonin - metabolism; Risk Factors; Self destructive behavior; Self-Injurious Behavior - genetics; Self-Injurious Behavior - metabolism; Self-Injurious Behavior - psychology; Selfinjury; Serotonin - metabolism; Serotonin Plasma Membrane Transport Proteins; Suicide; Suicide - prevention & control; Suicide - psychology; Tryptophan Hydroxylase - genetics; Tryptophan Hydroxylase - metabolism; Human; 5-HT2A serotonin receptor; Enzyme; Genetic variant; Serotonine receptor; Genetic determinism; Amine oxidase (flavin-containing); Suicide attempt; Tryptophan 5-monooxygenase; Risk factor; 5-HT1B serotonin receptor; Genetics; Candidate gene; Oxidoreductases; Molecular biology; 5-HT2C serotonin receptor; Comparative study; Polymorphism
• DOI: 10.1017/S0033291703007463
• ISSN: 0033-2917

Background. There is a heritable component to suicidal behaviour, encouraging the search for the associated risk alleles. Given the putative role of the 5-HT (5-hydroxytryptamine; serotonin) system in suicidal behaviour, serotonergic genes are leading candidates. In particular, several studies have reported an association with variants in the tryptophan hydroxylase (TPH) gene. Method. We studied six serotonergic gene polymorphisms in a well-characterized sample of 129 deliberate self-harm subjects and 329 comparison subjects. The polymorphisms were TPH (A779C), 5-HT transporter (5-HTT, LPR S/L), monoamine oxidase A (MAOA G941T), 5-HT1B receptor (HTR1B G861C), 5-HT2A receptor (HTR2A T102C), and 5-HT2C receptor (HTR2C Cys23Ser). Genotyping was done using polymerase chain reaction (PCR)-based assays. The primary analyses compared allele and genotype frequencies between cases and controls. There were a limited number of planned secondary analyses within the deliberate self-harm group. Results. The TPH A779 allele was more common in deliberate self-harm subjects than in controls (OR 1·38, 95% CI 1·02–1·88; P=0·03). None of the other polymorphisms was associated with deliberate self-harm. Within the deliberate self-harm group there were no associations with impulsivity, suicide risk, lifetime history of depression, or family history of deliberate self-harm. Conclusions. Our data extend the evidence that allelic variation in the TPH gene is a risk factor for deliberate self-harm. No evidence was found to implicate the other polymorphisms.