By David Ljunggren
OTTAWA, Jan 31 (Reuters) -- Canadian doctors report the discovery of a
genetic mutation that increases the chance of an individual committing suicide.
They predict that a test to identify those at high risk of killing themselves
could be available by 2002.
The results of a 10-year study by a team at the Royal Ottawa Hospital are
a clear sign that suicide is a largely genetic phenomenon and not related, as
often thought, to weakness of character.
There are enormous implications to the findings. Creation of a successful
test may lead to more careful treatment of depressed patients who carry the
mutation, but may raise fears that those with the marker could be discriminated
against.
The team found that depressed people with a mutation in the gene encoding
for a serotonin 2A receptor -- a message-carrying chemical linked to mood --
were more than twice as likely to commit suicide than those without the
mutation.
However, team member Dr. Pavel Hrdina cautioned that the study's results
would have to be duplicated before they could be deemed scientifically valid.
"The major finding of the study was that suicidal tendencies were much
more frequent in depressed individuals carrying the (mutation)," he told
Reuters.
Hrdina said a "suicide test" could be devised within 2 years to help
identify those depressed people at higher risk of killing themselves.
"This is a warning sign, an early marker. There might be depressed people
who don't have suicidal tendencies, who wouldn't know at the time (they had the
mutation). Those patients would be more closely watched than others," he said.
According to the World Health Organization, suicide was the 12th leading
cause of death in 1998, when 948,000 people died of self-inflicted injuries.
Experts predict that cases of suicide and depression will soar over the next 20
years.
Hrdina said that depressed people with suicidal tendencies almost
certainly carried other genetic mutations that combined to trigger suicidal
inclinations.
The serotonin 2A receptor mutation was therefore a reliable sign that
someone might kill themselves rather than being the only cause for suicide.
The results have enormous moral implications. For example, what would
happen if companies forced their employees to take the test and then
discriminated against those found to carry the mutation? Would these people be
denied life insurance or barred from flying planes or driving school buses?
"That is a question which society will have to decide. The positive side
of this is that if there is a biological or genetic test, one can give hope that
with treatment this can be handled," said Hrdina.
"If this is just let go and we don't encourage people to (learn) about it
-- and they are not seeking medical help to treat their symptoms of depression
or suicidality -- they may eventually end up losing their lives," he added.
Dr. David Bakish, a suicide specialist on the team, said tests showed that
there was no reduction in the level of mutant serotonin receptor genes in
patients who had been successfully treated for depression.
"This is very meaningful. It suggests that some people may be biologically
predisposed to suicidal thoughts, and that suicide, so often stigmatized, is
hardly a character flaw," he said.
The Ottawa researchers started by studying the brains of people who had
killed themselves in Hungary, a country with one of the world's highest suicide
rates. The tests showed that many carried the mutated gene.
The team then carried out a long-term study on a group of 120 depressed
people in Canada.
"We divided the depressed patients into suicidal and non-suicidal and we
found the frequency of the gene variety was significantly higher in the suicidal
patients," Hrdina said. "We concluded that the carriers of this particular
combination in the gene were at double the risk for suicidal tendencies."
Hrdina said the Royal Ottawa Hospital team was now looking at whether
people with other mental disorders such as schizophrenia also carry the
mutation.
"There is a stigma about these things, people shy away. But it will help
them when they realize (being suicidal) is not a crazy state, or something that
comes out of the air and cannot be handled, but has a biological link," Hrdina
said.
The team's findings will be published in the February 7th issue of the
American Journal of Medical Genetics.
