The search for genetic risk factors associated with suicidal behavior.
BACKGROUND
Suicide and suicidal behavior are prevalent among individuals with psychiatric disorders, including alcohol dependence. A genome screen was performed in multiplex alcohol dependent families ascertained as part of the Collaborative Study on the Genetics of Alcoholism to identify chromosomal regions of interest related to two types of suicidal behavior: suicide attempts and suicidality.


METHODS
Sibling pair analyses were used to conduct linkage analyses using both qualitative and quantitative suicide-related phenotypes. The qualitative trait of "suicide attempts" was examined using 59 affected sibling pairs. The quantitative trait of "suicidality" was examined using all possible 1366 sibling pairs and 705 independent sibling pairs.


RESULTS
For the qualitative phenotype suicide attempts, chromosome 2 yielded a maximum lod score of 4.2. For the quantitative suicidality index, a maximum lod score of 1.8 was observed on chromosome 3, and a lod score of 1.5 was found on chromosome 1.


CONCLUSIONS
This study represents the first genome-wide scan of suicidal behavior. Significant evidence of linkage was found on chromosome 2 for the phenotype suicide attempts, the same chromosomal region previously reported to be linked to alcohol dependence in this sample. This finding does not seem to be due solely to an association between suicide and alcohol dependence. There was more modest evidence of linkage to chromosomes 1 and 3 for suicidality; however, these findings did not reach statistical significance. There was no overlap in findings for these two phenotypes of suicidal behavior.
Hesselbrock
Victor
V
Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut, USA. hesselb@psychiatry.uuchc.edu
Dick
Danielle
D
Hesselbrock
Michie
M
Foroud
Tatiana
T
Schuckit
Marc
M
Edenberg
Howard
H
Bucholz
Kathy
K
Kramer
John
J
Reich
Theodore
T
Goate
Alison
A
Bierut
Laura
L
Rice
John P
JP
Nurnberger
John I
JI
D000437:Alcoholism / Q000453:epidemiology / Q000235:genetics*; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics; D005260:Female; D008040:Genetic Linkage / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000453:epidemiology / Q000235:genetics*; D006801:Humans; D008126:Lod Score; D008297:Male; D010641:Phenotype; D012307:Risk Factors; D013405:Suicide / Q000706:statistics & numerical data