Children who have an older sibling with autism are seven times more likely than other kids to be diagnosed with the disorder themselves, according to a new study from Denmark.
That extra risk is smaller than had been suggested in earlier studies.
Researchers also found a higher-than-average risk among children whose older half-sibling had an autism spectrum disorder (ASD) especially if the two kids shared the same mother.
I think a lot of autism researchers agree that the causes of autism are many and its very complex, Therese Gronborg, who led the study at Aarhus University, said.
If it was only genetics we would see a much higher recurrence rate among siblings, she said.
About one in every 88 U.S. children has an ASD, according to the Centers for Disease Control and Prevention.
For their new study, Gronborg and her colleagues used birth, civil and psychiatric registries to track 1.5 million children born in Denmark between 1980 and 2004.
Through 2010, just more than 13,000 of them had been diagnosed with an ASD. That included 276 children with an older sibling with autism who were also diagnosed with the disorder.
The researchers found the likelihood of a younger sibling being diagnosed with autism when an older sibling had an ASD varied between 4.5 and 10.5 per cent, with an average of about 7 per cent.
There was no clear increasing or decreasing trend during the study period.
Go here to see the original:
Study shows siblings’ autism risk is greater