Autism-linked genes often differ between siblings

In families that have more than one child with autism, the gene variations underlying each child's disorder often differ, new research shows. Researchers have long known that autism is a complex disorder. Experts have suspected that the development of autism involves both genetic susceptibility and environmental exposures that aren't yet fully understood.
Now the new study suggests the genetic component is even more complicated than previously thought.
"The genetic risk for autism is extremely complex," said lead researcher Dr. Daniel Geschwind. He is a professor of human genetics at the David Geffen School of Medicine at University of California, Los Angeles.
"Even in 'multiplex' families [where more than one child has autism], it's not as obvious as thought," he said.
In general, experts believe that certain circumstances need to be in place for children to develop autism: a genetic susceptibility, coupled with some kind of environmental stressor during a critical period of brain development.
Many gene variants have been linked to autism risk, and studies have suggested some environmental culprits -- such as low birth weight, certain infections during pregnancy and prenatal exposure to heavy air pollution and pesticides, according to the nonprofit organization Autism Speaks.
The evidence that genes are critical in autism comes, in part, from studies of families. When parents have a child with autism, they have about a one-in-five chance of having a second child affected, a previous study in the journal Pediatrics found.
It's reasonable to expect that those two siblings would share the same autism-linked genes, Geschwind said. But that's not what his team found.
    HealthDay

Autism-linked genes often differ between siblings

In families that have more than one child with autism, the gene variations underlying each childs disorder often differ, new research shows. Researchers have long known that autism is a complex disorder. Experts have suspected that the development of autism involves both genetic susceptibility and environmental exposures that arent yet fully understood. Now the new study suggests the genetic component is even more complicated than previously thought. The genetic risk for autism is extremely complex, said lead researcher Dr. Daniel Geschwind. He is a professor of human genetics at the David Geffen School of Medicine at University of California, Los Angeles. Even in multiplex families [where more than one child has autism], its not as obvious as thought, he said. In general, experts believe that certain circumstances need to be in place for children to develop autism: a genetic susceptibility, coupled with some kind of environmental stressor during a critical period of brain development. Many gene variants have been linked to autism risk, and studies have suggested some environmental culprits -- such as low birth weight, certain infections during pregnancy and prenatal exposure to heavy air pollution and pesticides, according to the nonprofit organization Autism Speaks. The evidence that genes are critical in autism comes, in part, from studies of families. When parents have a child with autism, they have about a one-in-five chance of having a second child affected, a previous study in the journal Pediatrics found. Its reasonable to expect that those two siblings would share the same autism-linked genes, Geschwind said. But thats not what his team found. HealthDay