UniSci According
to the U.S. Centers for Disease Control and Prevention (CDC), suicide is the 8th
leading cause of death in the U.S. (and the 3rd for those in the 15-24 age range).
Two articles in the current issue of Molecular Psychiatry from researchers
in France and in Switzerland have identified variations (polymorphisms) in two
genes that are associated with suicidality -- the tendency to kill oneself. These
findings suggest that suicidality may have a genetic basis.
In the first
article, "Suicide attempts and the tryptophan hydroxylase gene," the authors,
from the Department of Psychiatry, Carˇmeau Hospital, Nimes, France; Department
of Psychological Medicine and Psychiatry, Lapeyronie Hospital and University Department
of Psychiatry, La Colombi¸re Hospital Montpellier, France; Henri Mondor and Albert
Chenevier Hospitals, Crˇteil, France; and the Department of Psychiatry, Geneva
University Hospital, Geneva, Switzerland, point out the following:
A specific
genetic vulnerability for suicidal behavior is strongly suggested by the results
of epidemiological genetics studies. Several lines of evidence suggest that regulation
of serotonin neurotransmission is a key factor for this vulnerability.
Recent
studies have investigated the involvement of the gene coding for the tryptophan
hydroxylase (TPH), the rate-limiting enzyme in serotonin biosynthesis, in the
genetic susceptibility to suicidal behavior.
In this case-control study,
the authors investigated seven polymorphisms spanning the entire TPH gene in 231
suicide attempters and 281 controls.
Significant associations were found
between variants within the 3' noncoding region and suicide attempt. The association
was strongest for subjects who had attempted suicide by violent means and who
had a history of major depression.
The results, and those of previous
studies, suggest that a genetic variant of the 3' part of the TPH gene may be
a susceptibility factor for a phenotype combining suicidal behavior, mood disorder
and impulsive aggression.
(Citation source: Molecular Psychiatry 2001 Volume
6, number 3, pages 268-273.)
In the second article, "Association between
violent suicidal behavior and the low activity allele of the serotonin transporter
gene," the authors, from the Department of Psychological Medicine and Psychiatry,
Lapeyronie Hospital and University Department of Psychiatry, La Colombi¸re Hospital
Montpellier, France; Department of Psychiatry, Carˇmeau Hospital, Nimes, France
and the Department of Psychiatry, Geneva University Hospital, Geneva, Switzerland,
declare:
There is compelling evidence that serotonin system dysfunction
is associated with suicidal behavior. Some data suggest that this association
is stronger with violent suicidal behavior.
The genetic susceptibility
to suicidal behavior may involve a functional polymorphism (S/L alleles) in the
promoter region of the serotonin transporter gene. The S allele of this gene has
been found to be associated with a lower level of expression of the gene and lower
leve]s of 5-HT uptake.
The authors genotyped 51 violent suicide attempters
and 139 controls with no history of suicidal behavior, all of West European Caucasian
origin.
The frequencies of the S allele and the SS genotype were significantly
higher in the violent suicide attempters than in the controls. The odds ratio
for the SS genotype vs the LL genotype was 3.63 (95% CI (l.Z7-10.40)).
Together
with previous reports, the present finding suggests that a change in expression
of the gene encoding the 5-HT transporter may be involved in violent suicide behavior.
(Citation
source: Molecular Psychiatry 2001 Volume 6, number 3, pages 338-341.)
For
further information on both articles, please contact Dr. Philipe Courtet, Department
of Psychological Medicine and Psychiatry, Lapeyronie Hospital, 34295 Montpellier
Cedex 5, France. Dr. Courtet can be reached by email at this address.
Molecular
Psychiatry is published by the Nature Publishing Group. It is edited by Julio
Licinio, M.D., Professor of Psychiatry, UCLA Gonda Center, Los Angeles, CA. |
