A new analysis of DNA from more than 20,000 people with autism identifies 12 regions in the genome that harbor inherited risk factors for the condition.
Rare, spontaneous mutations account for only about 10 percent of autism cases, and they cannot explain why autism runs in families; common variants are, by contrast, thought to account for up to half of the risk for autism.
…[Researchers] performed a genome-wide association study (GWAS), searching for single-letter variants that occur more frequently in people with autism than in controls. They found that 88 variants are associated with autism.
They confirmed 53 of these variants in an independent sample of 2,119 autistic people and roughly 142,000 controls. Applying statistically stringent criteria, they identified five variants in all that meet the definition of an autism risk factor.
The newly identified variants lie within or near 15 genes, many of them expressed in the brain. The most strongly implicated is KCNN2, a gene that controls potassium ion flux in neurons. And some of the genes, including KMT2E and PTBP2, are known to carry de novo mutations implicated in autism.
Many of the genes are expressed during mid-fetal development, when autism genes are typically most active.
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