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Siblings of Children with Autism Have Language Delays
Among siblings, 20 percent had
received a diagnosis of language
delay or speech problems early in
life; © SXC
Siblings of children with autism have more frequent language delays and other subtle characteristics of the disorder than previously understood. Girls also may be mildly affected more often than recognised in the past.
A new study, led by researchers at Washington University School of Medicine in St. Louis, found mild traits, not strong enough to provoke a diagnosis of autism, seem to be present in the siblings of affected children at significantly higher rates than seen in the general population.
"Mild symptoms, called quantitative traits, may be confounding studies that compare children with autism to their siblings," says first author John N. Constantino. "Researchers presume one child is affected, and the other is not, but our findings suggest that although one child may have autism while the other does not, it's very possible both children are affected to some degree by genes that contribute to autism."
The study found that approximately one in five siblings thought to be unaffected experienced language delays or speech problems early in life. The researchers also noticed many female siblings had subtle traits, but few had full-blown autism spectrum disorders. Boys are thought to be affected four times more often than girls. But when the researchers used standardised methods to account for the presence of quantitative traits, the rate looked more like three affected boys for every two affected girls.
"The gender difference may not be as pronounced as we once thought it was," Constantino says. "If we rely only on a professional diagnosis of autism to determine who is affected, then boys vastly outnumber girls. But it may be that many girls are being missed."
The data comes from almost 3,000 U.S. children in 1,235 families who are part of the Interactive Autism Network, a national online research registry. For this study, parents provided information about their children using the Social Responsiveness Scale, a survey developed at Washington University that identifies traits associated with autism and autism spectrum disorders such as Asperger Syndrome and Pervasive Developmental Disorder.
One striking finding was that among siblings, 20 percent had received a diagnosis of language delay or speech problems early in life. And half of them had particular qualities of speech that are autistic in nature. So the investigators believe that what is aggregating in these families is more than just the full syndrome of autism. In about 11 percent of families, more than one sibling has autism, and in many others, these subtle, quantitative signs and symptoms indicate many undiagnosed children are affected as well.
REHACARE.de; Source: Washington University School of Medicine
- More about the Washington University School of Medicine at www.medicine.wustl.edu
( Source: REHACARE.de )