Casting for the Cure

Autism is a congenital mental disorder, which is estimated to affect one of 150 births in the United Sates. It is among a group of disorders, including Asperger syndrome, which are classified as the ASD (autism spectrum disorders). Autism affects the social and communication development of children and is usually apparent before the age of two. It may cause restrictive and repetitive behavior, disruptive to the child’s caretakers, and possibly dangerous to the child itself. While autism can occur at all IQ levels, there is a higher incidence of mental retardation among autistic children, and 20 to 30 percent may have seizures. Some autism sufferers are savants, with an area in which they excel such as music, baseball statistics, or some other specific interest.

Autism has been blamed on many things, including bad reactions to childhood immunizations, but studies indicate that is almost certainly a genetic disorder. How the genes are disrupted to produce the behavioral mutations has not been clearly understood, but researchers recently studied more than 100 families with a significant rate of autism and say they have identified at least six new genes that appear to contribute to the disorder. The study, published in the journal Science, substantiates that autism is not just a single simple disorder, but can be caused by a range of factors, both genetic and environmental.

Dr. Christopher Walsh and Dr. Eric Morrow of Harvard Medical School in Boston, and colleagues, studied 104 volunteer families in the United States, Pakistan, Turkey, Jordan, Saudi Arabia, Kuwait, Oman, Qatar, and the United Arab Emirates with high incidence of autism. In the Middle Eastern families cousins commonly marry, making the likelihood of passing on recessive genes more probable, and Middle Eastern families usually have more children than United States families providing more subjects to study. In 88 of the Middle Eastern study families, where the parents are first cousins, autism appears to be caused by faulty DNA and something in the physical or social environment of a child after birth.

“There appear to be many separate mutations involved, with each family having a different genetic cause.” Dr. Thomas Insel, director of the National Institute on Mental Health, said in a statement. The institute helped pay for the study.

According to Dr. Walsh, “Autism symptoms emerge at an age when the developing brain is refining the connections between neurons in response to a child’s experience.” The study indicated that certain important genes are dependent on experience triggered neural activity. Disruption of the process may be a mechanism of autism-associated mutations. The findings did offer some hopeful findings, not all of the mutations resulted in missing or damaged genes, the genes were simply turned off. Walsh, also a Howard Hughes Medical Institute investigator, noted that studies have shown that enriched learning environments can help some children with autism. Extra training may help activate pathways in the brain, bypassing the broken on/off switches.

The study has changed previous thinking that a handful of genetic mutations caused most autism cases, researchers now believe that most cases have unique causes. Some of the mutations aren’t in the coding genes that control the action of proteins in the brain, but are in the genes that regulate other genes and have a more limited influence, suggesting that the disorder can be treated in some cases.

According to Dr. Morrow, “If we can figure out how to compensate for these more subtle deficiencies with some sort of behavioral treatment or medicine,” it may help the brain develop properly.