Suicidal behavior in twins: a replication.
OBJECTIVE
Our two previous reports showed that monozygotic (MZ) twins were significantly more concordant for both completed suicide and attempted suicide than dizygotic (DZ) twins. We wished to replicate the finding that MZ co-twins showed greater concordance for suicidal behavior.


METHODS
We collected a new series of 28 twin pairs in which one twin had committed suicide.


RESULTS
We found that 4 of the 13 MZ twin pairs were concordant for suicidal behavior compared with 0 of the 15 DZ twin pairs (P=0.035).


CONCLUSIONS
These data confirm our previous reports that MZ co-twins show greater concordance for suicidal behavior than DZ co-twins, consistent with genetic influence.
Roy
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A
Psychiatry Service, Department of Veterans Affairs, VA Healthcare System, East Orange, NJ 07018, USA.
Segal
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NL
D000293:Adolescent; D000328:Adult; D001601:Bereavement; D002140:California; D004200:Diseases in Twins / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012306:Risk; D013405:Suicide / Q000523:psychology*; D013406:Suicide, Attempted / Q000523:psychology*; D014429:Twins, Dizygotic / Q000235:genetics / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics / Q000523:psychology