December 13, 2012 - Autism Spectrum Disorders (ASDs) are marked by a suite of symptoms, arising from atypical brain development that results in problems with socialization, communication, and behaviour.
The results of three new studies developed by the U.S. 'Centerfor Disease Control and Prevention' which were recently published in the journal, 'Nature' involving hundreds of families with autism, have found that spontaneous mutations can occur in a parent's sperm or egg cells which increase a child's risk for autism. When the mutation occurs in part of the genome needed for brain development, it poses a 5 to 20 times higher risk of developing autism, which confirms that the location is the risk, and not the size of the genetic anomaly. The studies suggest that mutations in parts of genes that code for proteins called 'exome' play a significant role in autism. Fathers are four more times likely than mothers to pass these mutations on to their children.
"…studies found that new mutations occurred 4 times more frequently in sperm cells than in egg cells, and the older the father, the more likely he was to have sperms with these spontaneous mutations."
Dr. Evan Eichler
University of Washington April 2012
Scientists have found that genetic causes only explain about 10% of the cases, and recent studies have pointed to environmental factors, possibly arising at conception, as potential triggers. Joseph Buxbaum, Director of the 'Seaver Autism Center' at Mount Sinai School of Medicine in New York and a co-author of one of the studies, said,"… the combined results from the three studies suggest some 600 to 1,200 genes may contribute to the risk for developing autism. The trick will be identifying specific networks in the brain in which these genes interact, so that researchers can begin to develop new treatments."
Dr. Evan Eichler and colleagues at the University of Washington in Seattle found that new mutations occurred 4 times more frequently in sperm cells than in egg cells, and the older the father, the more likely he was to have sperms with these spontaneous mutations.
A recent study in 2012 by the U.S. 'Center for Disease Control and Prevention' shows an estimated 1 in 88 children have autism or a related disorder, compared to 1 in 155 in 2002. While there is no new Canadian evidence, a 2006 study led by Dr. Eric Frombonne at McGill University has found that 1 in 154 children have an Autism Spectrum Disorder.
Suzanne Lanthier, Executive Director of the advocacy group, 'Autism Speaks Canada' acknowledged that while more awareness and better diagnostic tools have contributed to the rise in number of children identified with the disorder, "…more children are falling prey to the disorder."
The U.S. Center for Disease Control and Prevention found that Autism Spectrum Disorders are almost 5 times more common among boys than girls. A 2008 study that looked at 8-year-old children showed 1 in 54 boys diagnosed with the condition compared to 1 in 252 girls. ASD's can be mild or severe, but in all cases, they have difficulty communicating and making friends.
Statistics on Diagnosis
The 'U.S. Center for Disease Control and Prevention' found that Autism Spectrum Disorders are almost 5 times more common among boys than girls.
- More than 50% of the children were 5 years old or older when they were first diagnosed with ASD and less than 20% were diagnosed by the age of two. The American Academy of Pediatrics recommends that pediatricians screen children for autism at 18 months of age.
- More than 50% of the children diagnosed with ASD use psychotropic medications including anti-psychotics, anti-depressants, stimulants and mood stabilizers.
- General physicians were most likely able to pick up the child's diagnosis if they were under the age of five and children over the age of five were most likely diagnosed by a psychologist or psychiatrist.
- Children aged five and older were 50% more likely to be diagnosed with autism when reviewed by a panel of doctors as opposed to a single doctor or psychologist.