Regressive-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 editors@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. Further Readings: Bower, B. 2004. Brain development disturbed in autism. Science News 166(July 31):78. Available to subscribers at http://www.sciencenews.org/articles/20040731/note16.asp. ______. 2002. Autism leaves kids lost in face. Science News 161(June 29):408. Available to subscribers at http://www.sciencenews.org/articles/20020629/note9.asp. ______. 2000. Gene implicated in development of autism. Science News 158(Dec. 16):390. Available to subscribers at http://www.sciencenews.org/articles/20001216/fob5.asp. ______. 2000. When autism aids memory. Science News 158(July 29):72. Available to subscribers at http://www.sciencenews.org/articles/20000729/note13.asp. Christensen, D. 2002. The persistent problem of cystic fibrosis. Science News 161(Jan. 26):59-60. Available to subscribers at http://www.sciencenews.org/articles/20020126/bob11.asp. Fackelmann, K. 1995. Variations on a theme. Science News 147(May 6):280-281. Available at http://www.sciencenews.org/pages/sn_edpik/ms_3.htm. Parsell, D. 2004. Assault on autism. Science News 166(Nov. 13):311-312. Available at http://www.sciencenews.org/articles/20041113/bob8.asp. Travis, J. 2004. Drug fails in autism study. Science News 166(Jan. 31):76. Available to subscribers at http://www.sciencenews.org/articles/20040131/note10.asp. ______. 2003. Autism advance: Mutated genes disrupt nerve cell proteins. Science News 163(April 5):212. Available to subscribers at http://www.sciencenews.org/articles/20030405/fob4.asp. Sources: S. Jill James University of Arkansas for Medical Sciences Department of Pediatrics 1120 Marshall Street, Slot 512-40B Little Rock, AR 72202-3591 http://www.sciencenews.org/articles/20050416/note14.asp >From Science News, Vol. 167, No. 16, April 16, 2005, p. 254. Copyright (c) 2005 Science Service. All rights reserved. http://www.sciencenews.org/view/generic/id/6086/title/Blood_hints_at_autisms_source