A new study by Harvard researchers suggests that for some autistic children, the disorder originates from gene defects that can be switched on and off by mental activity.
The findings bring new hope to the devastating disorder and may eventually help lead to treatments in the future.
An estimated one out of every 150 U.S. children has autism, according to the U.S. Centers for Disease Control and Prevention.
The study supports previous research that autism may result from problems in the complex process by which some networks of brain cells grow and others die during the first few years of a child’s life.
Three of the six genes marked in the new study are regulated by “neuronal activity” – doing, feeling, thinking – which in theory, suggests that altering the experiences of autistic children could help to change the course of the disorder.
The genes associated in the study are those that interact with the environment and the ones that are involved in helping the brain to translate what it sees from the environment. If these genes are able to be activated by another mechanism, autistic children may be able to receive treatment from the disorder, said Dr. Christopher A. Walsh, a neurologist at Children’s Hospital in Boston.
Researchers agree that the discovery that some “autistic genes” are also “experience genes” is hopeful.
The study reveals that environmental experiences and influences that shape brain development after birth are not insignificant,” said Isabelle Rapin, a pediatric neurologist at Albert Einstein College of Medicine.
Based on studies of families with twins and multiple children affected by autism, genes clearly play a large factor in the disorder. However, the genetic cause of autism is only known for about 15 percent of all cases.
For the study, Walsh and his team recruited participants from the Middle East, an area of the world known largely for first-cousin marriages and large families – both characteristics known to increase the odds of finding rare genes.
88 families with cousin marriages and a high occurrence of autism were included from Arabia, Jordan, Kuwait, Pakistan, Qatar, Saudi and Turkey.
Researchers compared the DNA of family members to search for “recessive mutations” – where both parents are healthy and free of genetic defects, but a child inherits that defect from both parents and becomes sick.
In some families, large areas of missing DNA regions were found to follow the recessive rule. While the missing regions varied among families, it affected five or more genes that play a role in autism.
All genes appear to be part of a network that is the foundation of basic learning – how neurons relate to new experiences by forming connections between one another, called a “synapses.”
Earlier research found the same underlying issue that also suggested autism is possibly a synaptic disorder.
Autism is a brain disorder that affects a person's ability to communicate, form relationships, and respond to the environment. Individuals can have mild, moderate or severe autism. Some people with autism are highly functional while others are mentally retarded, mute, or have severe problems with language.
The study was published in the July issue of Science Magazine.