Researchers have discovered a genetic defect responsible for
1 percent of the various forms of autism, they reported Wednesday.
Identifying the genetic defect could offer another way to screen
early for the disease, Moreover, doctors could help children with treatments
that can reduce some effects for the developmental disorder, researchers said.
“If we can identify children at risk for autism very
early, we have the chance to intervene early while the brain is still
developing,” says Annette Estes of the University of Washington's
Autism Center Research Program.
This discovery comes after researchers at the California
Department of Public Health on Monday said that removing thimerosal from all
recommended infants vaccines as a precautionary measure in March 2001 had no
effect on reducing the number of children suffering from autism. They reported
that autism rates in California
have continued to climb, from 3 per 1,000 in 2003 to 4 per 1,000 in 2007. The
only childhood vaccines that contain more than trace amounts of thimerosal are
multiple-dose vials of some flu vaccines.
Researchers in Boston and Chicago independently
identified a genetic variation in a region of the DNA called chromosome 16 that
is associated with about 1 percent of all autism cases. They also said that the
abnormality is often inherited.
The discovery is not new as David Miller, a researcher at
Children’s Hospital in Boston
and a co-author of one of the studies said that about 15 percent of autism
cases have a known genetic cause.
Researchers at University
of Chicago, who published
their results in Human Molecular Genetics, said the loss of a small portion of
chromosome 16 results in a corresponding loss of 25 genes. At least three of
those genes are believed to influence behavior, making them prime candidates
for autism research.
"The hope is that eventually, if we can find genes that
lead to brain mechanisms, we can think about treatment," said Fred
Volkmar, an autism expert and director of the child study center at the Yale
University School of Medicine, who was not involved in either study.
The second study, made by researchers from a group of Boston hospitals and universalities
known as the Autism Consortium, was published Wednesday in the online issue of
the New England Journal of Medicine.
The researchers scanned DNA samples from more than 3,000 people,
including 1,441 diagnosed with autism to identify the link to chromosome 16. They discovered 13 children who were missing snippets of DNA
and 11 who had duplications. In all the cases, the children had autism or
related problems, the researchers reported.
Miller said that his team plans further study of the region
to identify exactly which of these genes is most closely linked to autism.
“We think that this chromosome 16 region may have some genes that are very
important in brain development, and when changes happen in those genes, it may
be the cause of many cases of autism. We have to figure out what is it about
the combination of this chromosome 16 with other genetic factors, or other
environmental factors,” he said.
