Researchers believe they have localized a
major susceptibility gene for schizophrenia on
chromosome 1, according to a study published in
today's edition of the journal Science.
Led by Dr. Anne Bassett, the study’s senior
author, researchers collected DNA samples and over
a 12-year period assessed 300 individuals from 22
Canadian families with a high incidence of
schizophrenia, a serious psychiatric illness that
affects one per cent of the general population.
Bassett and her colleagues believe there are
several genes involved and there may be
environmental factors that interact to ultimately
cause the illness.
"Even though schizophrenia is complex, we
decided to look for rare families where the
illness looked like it was being inherited. The
families participating in the study are key -
they are large and have two or more members with
schizophrenia," says Bassett, an associate
professor of psychiatry at the University of
Toronto and head of the schizophrenia research
program at the Queen Street site of the Centre for
Addiction & Mental Health (CAMH).
"If we compare the human genome to a map of the
world and gene localizing to finding the
neighbourhood the gene lives in, previous studies
have been able to say that there may be a gene in
North America, maybe even in Canada," she says.
"Our study tells us that there is a gene
predisposing to schizophrenia in the neighbourhood
of downtown Toronto and that we should be able to
pinpoint the exact location in the next step of
Using a lod score analysis - the same
method used to locate genes for breast cancer
- the study’s lead author, Dr. Linda
Brzustowicz of Rutgers University in New Jersey,
localized a schizophrenia susceptibility gene to a
small region of chromosome 1, likely the "address"
of the susceptibility gene.
"This finding is very strong," Brzustowicz
says. "This is approximately 100 times stronger
evidence for the existence of a schizophrenia gene
than reported in previous studies."
The magnitude of the chromosome 1 result gives
scientists realistic hope that further research
will lead them to the schizophrenia gene that is
in this region of the human genome.
"These results should pave the way for
discovering the other genes which may play a role
in schizophrenia," says Bassett, who initiated
this study 12 years ago while on a research
fellowship at the New York State Psychiatric
Institute where Brzustowicz and another of the
study’s authors, Dr. William Honer, now at the
University of British Columbia, also trained.
The authors believe knowing about the nature
and function of genes will provide insights into
the underlying biological mechanisms of
schizophrenia and should lead to improved
treatments for the disease.
Other researchers involved in this study are
Dr. Eva Chow, assistant professor of psychiatry at
U of T and a research psychiatrist at CAMH, and
Kathleen Hodgkinson, a genetic counsellor and
graduate student with Dr. Bassett.
This research, which has involved longstanding
multicentre and multidisciplinary teamwork, has
received funding from Canadian and American
sources over the past 12 years. These include: the
Medical Research Council of Canada, Ontario Mental
Health Foundation, Bill Jefferies Research
Foundation, Ian Douglas Bebensee Foundation, EJLB
Foundation, Scottish Rite Schizophrenia Research
Program, National Institute of Mental Health,
Center for Inherited Disease Research, National
Alliance for Research on Schizophrenia and
Depression, and individual donations.
The Centre for Addiction and Mental Health, a
World Health Organization Centre of Excellence and
a teaching hospital fully affiliated with the
University of Toronto, was established in 1998
through the merger of the Addiction Research
Foundation, the Clarke Institute of Psychiatry,
the Donwood Institute and the Queen Street Mental
Health Centre. - By Steven de Sousa
[Contact: Steven de