Some children with autism carry rare mutations in DNA segments that flank genes and control their expression—and they tend to inherit these mutations from their unaffected fathers, according to a study published [April 19] in Science. The finding is unexpected because most studies implicate mutations inherited from mothers in autism risk. For this reason, some experts are skeptical of the results. The study is the largest yet to explore how mutations outside of genes contribute to autism: It is based on an analysis of 9,274 whole genomes. And it focuses on ‘structural variants’—deletions or duplications in DNA—in these noncoding regions.
…[Researcher Jonathan Sebat] found that children with autism inherit about twice as many rare variants from their fathers as would be expected by chance. By contrast, rare variants inherited from mothers make a minimal contribution.
The results are also at odds with a prevailing theory of autism, the ‘female protective effect.’ According to this theory, women are somehow protected from mutations that might trigger autism, but sometimes pass the mutations down to their sons.
Sebat says the findings are not inconsistent with this theory. He says autism could stem from a combination of a powerful coding mutation inherited from the mother and a less powerful noncoding mutation inherited from the father.
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