Altered DNA methylation in a severe subtype of idiopathic autism: Evidence for sex differences in affected metabolic pathways.
Severe autism carries a girl-specific methylation fingerprint tied to mitochondrial pathways.
01Research in Context
What this study did
Weiss et al. (2021) compared DNA methylation patterns in severely affected autistic people and their siblings.
They looked for sex differences in the tagged genes and pathways.
The team used a case-control design and focused on idiopathic autism.
What they found
Girls with severe autism showed unique methylation marks in genes that run mitochondria and other metabolic jobs.
Boys did not show the same pattern.
The signals point to energy-making pathways that may shape how autism risk shows up in females.
How this fits with other research
Melnyk et al. (2012) first linked autism to both DNA hypomethylation and oxidative stress. W et al. extend that work by adding sex and mitochondria to the story.
Lehnhardt et al. (2016) and Koyama et al. (2009) showed cognitive sex differences in ASD. The new methylation data give a possible biological reason for those gaps.
Paolizzi et al. (2025) found parents rate autistic girls as more socially able than boys even when clinician scores match. The hidden mitochondrial signature in girls may help explain why their struggles are missed.
Why it matters
If you assess or treat girls with autism, know their biology can look different. Energy-related genes may influence how symptoms show and how they respond to stress or diet. When severe autism is suspected but signs feel subtle, consider that current tools may miss the female pattern. Push for deeper medical work-ups and plan interventions that account for possible mitochondrial needs.
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02At a glance
03Original abstract
This study investigates altered DNA methylation that may contribute to autism spectrum disorders. DNA methylation is an epigenetic mechanism for regulating the level at which genes are expressed, and is thus complementary to genetics and gene expression analyses which look at the variations in gene structure and gene products in cells. Here, we identify DNA methylation differences between autistic and sex-matched non-autistic siblings, focusing on a subgroup of severely affected individuals with language impairment to reduce the clinical heterogeneity among the cases. Our results show significant differentially methylated genes between the sibling groups that are enriched in autism risk genes as well as in signaling and biochemical pathways previously associated with the pathobiology of autism spectrum disorders. Moreover, we show for the first time that these differences are in part sex dependent, with differentially methylated genes in females associated with pathways that implicate mitochondrial dysfunction and metabolic disorders that may offer some protection to females against autism spectrum disorders. Further investigations of sex differences are required to develop a fuller understanding of the pathobiology, gene regulatory mechanisms, and differential susceptibility of males and females toward autism spectrum disorders.
Autism : the international journal of research and practice, 2021 · doi:10.1177/1362361320971085