People with schizophrenia have high rates of rare genetic mutations which appear to disrupt the developing brain, according to a new study.
Individuals with the devastating mental condition have three and
sometimes four times the number of rare genetic abnormalities that
healthy individuals do, and more of them affect genes regulating brain
The abnormalities consist of duplicated or deleted strands of DNA
and differ from person to person, so much so that the genetic
fingerprint of the disease is unique for every individual.
"We speculate that most people with schizophrenia have a different
genetic cause," said Mary-Claire King, professor of genome sciences at
the University of Washington in Seattle, who collaborated on the study.
"The mutations are individually rare, but share consequences
Schizophrenia is a chronic psychiatric disorder that afflicts about
one percent of the population. People with the illness suffer from
hallucinations, delusions, feelings of persecution and disorganised
Some of the symptoms can be managed with anti-psychotic medications,
but there is no cure.
Not that simple
Prior to the publication of this study in the journal Science, it was assumed
that genetic studies like this one would trace the origins of the
illness back to a cluster of common, or high frequency, genetic
But this paper suggests the genetic signature of schizophrenia, much
like autism, is more complicated than that, involving dozens or even
hundreds of genes, whose function has been disrupted by duplications or
deletions of DNA.
For this paper, the researchers from University of Washington, Cold
Spring Harbor Laboratory in New York and the US National Institutes of
Health studied a relatively modest number of people: 150 individuals
with schizophrenia and 268 healthy patients.
Many genes implicated
The study implicated 24 different genes in the disease, and yet
virtually every single mutation or copy number variation was different,
which suggests that studies of larger populations will implicate even
larger number of genes.
Many copy number variations are benign, but the researchers looked
only at rare abnormalities, and not only were they much more abundant
in the people with the disorder, but a preponderance of them were in
genes that affect communication between brain cells.
Specifically, 15 percent of schizophrenia patients who developed the
illness as adults had these rare DNA errors versus just five percent of
The rate jumped to 20 percent among patients who had a more severe
form of the illness that began in childhood or adolescence.
"This is an important new finding in the genetics of schizophrenia,"
said Thomas Insel, director of the US National Institute of Mental Health.
"Identifying genes prone to harbouring these mutations in brain
development pathways holds promise for treatment and prevention of
schizophrenia, as well as a wide range of other neurodevelopmental
brain disorders." – (Sapa-AFP)
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