That half of the family is on the spectrum and half not makes the Wiesenthals interesting to Molly Losh, director of the Neurodevelopmental Disabilities Lab at Northwestern University in Evanston, Illinois. Losh is studying the ‘broad autism phenotype,’ a subclinical constellation of traits — social behavior, language differences, sensory sensitivities — that appears in up to half of parents and siblings of autistic people. These subtle traits in relatives do not add up to autism but still serve as useful phenomena to study the condition, Losh says. “We think of it as the distilled expression of autism’s genetic liability.”
Most of what scientists know about autism genetics so far has come from studying rare and spontaneous mutations with powerful effects. Much less is known about common genetic variants, which occur in at least 1 percent of the population and account for most of the inherited risk for autism.
For many families, learning about the broad autism phenotype has real value outside the lab or clinic. When a parent realizes they might have attention issues or anxiety, or they aren’t picking up on subtle social cues, it can save their relationships, [Rebecca] Landa says. “These things don’t just live in the autism circle.”
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