Case-control meta-analysis of blood DNA methylation and autism spectrum disorder.
Shan V Andrews, Brooke Sheppard, Gayle C Windham and 10 others
PMID 29988321WHAT IT FOUND
Blood DNA methylation showed no genome-wide significant differences between children with autism and controls, though 48 sites reached suggestive significance.
These findings do not provide a diagnostic marker or clinical target for therapists.
Key findings
01No CpG sites reached Bonferroni-level significance in the meta-analysis of blood DNA methylation.
0248 CpG sites met or exceeded a p value < 1 × 10 − 4 , and 7 CpG sites reached a significance level of p < 1 × 10 − 5 .
03The study had 80% power to detect a 3.8% DNAm difference between cases and controls at a Bonferroni level of significance.
STILL TO COME
How it was doneWhat they found
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What it does not show
The study was underpowered to detect differences smaller than 3.8% in methylation levels. Blood samples may not accurately reflect methylation patterns in the brain, where ASD-related mechanisms likely originate. The case-control design collected samples after ASD onset, so observed differences could be consequences of the condition or environmental exposures rather than causes. The SEED sample showed significant differences in sex and genetic ancestry between cases and controls, which were adjusted for but remain potential confounders. The SSC sample consisted of sibling pairs, which may limit generalizability to the broader population compared to the population-based SEED sample.
Declared interests
The authors declared no competing interests. The work was supported by the NIH, the Simons Foundation, and the CDC.
The easy way to misread this
Do not interpret the 48 suggestive sites as diagnostic markers. They did not reach genome-wide significance, meaning the result is consistent with chance, and no clinical test can be built from these findings.