Placental methylome analysis from a prospective autism study.
Diane I Schroeder, Rebecca J Schmidt, Florence K Crary-Dooley and 5 others
PMID 28018572WHAT IT FOUND
Placental methylation did not distinguish children later diagnosed with autism from typical development overall.
One region near the DLL1 gene showed higher methylation in autism samples, but this was a small exploratory finding, not a clinical test.
Key findings
01Average placental methylation across the genome did not differ significantly between children later diagnosed with autism and typically developing children.
02One highly methylated region downstream of the DLL1 gene showed a significant methylation difference between autism and typical placenta.
03Pyrosequencing confirmed increased methylation in autism samples compared with typical samples at the DLL1 enhancer region.
STILL TO COME
How it was doneWhat they found
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What it does not show
The analysis included only 24 children with ASD and 23 typically developing children, so it is small. Most samples were from boys; only two in each diagnosis group were girls. The study used placental tissue from a high-risk sibling cohort, not from the general population. The methylation method had low coverage at individual CpG sites, so some differences could have been missed. The DLL1 finding was one region among many tested and needs confirmation in larger studies. Placental methylation was not shown to diagnose autism or guide therapy.
Declared interests
Funded by the National Institutes of Health, DOD, the National Institute of Environmental Health Sciences, and the U.S. Environmental Protection Agency. The paper does not report additional conflicts of interest.
The easy way to misread this
Do not conclude that placental methylation can identify autism at birth. The overall methylation patterns did not differ between groups, and the DLL1 result was a single exploratory finding in a small high-risk sample.