In families that have more than one child with autism, the gene variations underlying each child’s disorder often differ, new research shows.
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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, [Dr. Daniel] Geschwind said. But that’s not what his team found.
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[A] likely explanation [for this discrepency], Geschwind said, is this: Siblings who lack the inherited CNV of their brother or sister may have other, harder-to-pinpoint genetic factors — such as inherited variations in a wide number of genes.…
Geschwind said that his team’s findings underscore the complexity of current “genetic counseling” for autism: Even if you can tell parents of a child with autism that their second child isn’t carrying the same risk gene, that is no guarantee the child won’t develop autism.
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