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Autism-gene link strengthens mercury vaccine claim

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ri...@math.missouri.edu

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Jun 17, 2005, 11:40:59 AM6/17/05

(autistic children have a genetic trait which reduces their ability
to eliminate heavy metals from their bodies)

Science News Online

Week of April 16, 2005; Vol. 167, No. 16 Blood hints at autism's
source

Janet Raloff

>From San Diego, at the Experimental Biology 2005 meeting

Researchers have identified a biochemical peculiarity in the blood
of autistic children. The scientists say the finding could lead to
earlier diagnosis of this neurological disorder and a better
understanding of how certain genes may drive it.

Autism, which typically shows up in toddlers, is characterized by
limited language skills, poor social interaction, repetitive
behaviors, and limited interests. Autism often runs in families,
which suggests a genetic cause.

However, "the incidence of autism has gone up dramatically in the
last 15 years," notes S. Jill James, director of biochemical genetics
at Arkansas Children's Hospital in Little Rock. "Because genes don't
change that fast, this points to something in the environment as a
trigger," she says.

In a study of the blood of some apparently healthy children, the
biochemistry of one sample stood out. It came from an autistic boy.
Curious, James got blood samples from 20 other autistic children.
All exhibited a similar, unusual biochemical fingerprint, which
James has now confirmed in an additional 75 autistic children. None
in a comparison group of 75 neurologically healthy kids carried the
fingerprint in his or her blood.

The autistic youngsters had unusually low concentrations of the
antioxidant glutathione in their cells. Their ratio of active
glutathione to its inactive breakdown products also was unusually
low.

"This pattern is consistent with an inability to detoxify [poisons],
especially heavy metals," such as mercury or lead, James says.
That's because the antioxidant normally binds to heavy metals, and
the body then targets the molecular complex for elimination.

Any of several combinations of genes may predispose the body to low
glutathione concentrations. James suspects that autism develops
under the combined effect of several gene mutations that deplete
glutathione and of exposure of a child to heavy metals or other
poisons. One of the most controversial theories about autism is
that vaccines preserved with the mercury-containing chemical
thimerosal can cause the condition (SN: 11/13/04, p. 311:
http://www.sciencenews.org/articles/20041113/bob8.asp).

Dietary treatments could boost glutathione in children carrying
genes that reduce the antioxidant, says James.

If you have a comment on this article that you would like considered
for publication in Science News, send it to edi...@sciencenews.org.
Please include your name and location.

References:

James, S.J., S. Melnyk, and S. Jernigan. 2005. Low plasma methionine,
cysteine, and glutathione levels are associated with increase
frequency of common polymorphisms affecting methylation and glutathione
pathways in children with autism. Experimental Biology 2005. April
2. San Diego. Abstract.

James, S.J., et al. 2004. Metabolic biomarkers of increased oxidative
stress and impaired methylation capacity in children with autism.
American Journal of Clinical Nutrition 80(December):1611-1617.
Abstract available at http://www.ajcn.org/cgi/content/abstract/80/6/1611.