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Some autism
cases linked to
rare mutations
By Tina Hesman Saey
Each person with autism may have a
genetically distinct version of the developmental disorder, a new large-scale
study finds.
Rare variations in which part of a
person’s genetic blueprint is missing
or duplicated are responsible for some
cases of autism, the study shows. Such
missing or duplicated stretches of DNA,
known as copy number variants, have
been implicated in schizophrenia and
other diseases (SN: 4/25/09, p. 16).
Published online June 9 in Nature,
the new study shows that some people
with autism may be missing some or
all of one or more genes involved in the
development and function of the brain.
The findings could lead to improved
diagnosis of the disorder, perhaps even
in infants, and may give new direction to
research on drug treatments.
“The exciting thing about ... this study
is that it highlights biological pathways
that can be targets for therapy,” says
Geraldine Dawson, chief science officer
of Autism Speaks, a national organization that helped to fund the study.
Autism is a group of developmental
disorders that impair social interactions and often language development.
Researchers don’t know the exact causes
of autism, but genetic factors are strong
suspects. Studies of identical twins show
that when one twin has autism, about
90 percent of the time the other twin will
too. Autism affects about one in every
100 children in the United States and is
more common in boys.
Previous studies have indicated that
people with autism may have more copy
number variants overall than healthy
people do. But the new study found that
people with autism had the same num-
ber of deletions as people in a healthy
control group. People with autism
tended to have deletions that removed
parts or all of genes, however, while
healthy people tended to have deletions
affecting stretches of DNA that don’t
contain genes.
