Multi-omics causal inference of nuclear-encoded mitochondrial genes in autism spectrum disorder.

Scientists studied how genes that control the cell's 'power plants' (mitochondria) might contribute to autism. They found three specific genes that appear to influence autism risk: two genes (CRAT and PRDX6) seem protective against autism, while one gene (TMEM177) has different effects depending on whether it's active in the brain or blood. These genes help cells produce energy and protect against damage, suggesting mitochondrial health may play a role in autism development.

This study used advanced genetic analysis methods (Mendelian randomization) to investigate how nuclear genes that control mitochondrial function contribute to autism spectrum disorder (ASD) risk. Researchers integrated multiple types of genetic data (methylation, gene expression, and protein levels) across blood and brain tissues. They identified three mitochondria-related genes with evidence for causal relationships to ASD: CRAT and PRDX6 showed protective effects, while TMEM177 showed mixed effects depending on tissue type (risk-increasing in brain regions, protective in blood). These genes are involved in cellular energy metabolism, antioxidant defense, and mitochondrial assembly, supporting a biological pathway linking mitochondrial dysfunction to ASD susceptibility.

Findings suggest mitochondrial pathways involving energy metabolism and antioxidant defense may be therapeutic targets for autism. However, tissue-specific effects highlight the complexity of potential interventions. Further research needed to validate these genetic associations and translate into clinical applications.

Sample sizes not reported. Relies on existing genetic datasets which may have population or methodological biases. Causal inference based on genetic instruments may not capture full complexity of gene-environment interactions. Functional validation of identified pathways not performed.

Mitochondrial dysfunction is increasingly implicated in autism spectrum disorder (ASD), yet its causal genetic basis remains unclear. Mitochondria are maternally inherited organelles essential for neurodevelopment and cellular energy homeostasis, while most mitochondrial proteins are nuclear-encoded and follow Mendelian inheritance. Clarifying how genetically regulated mitochondrial gene activity relates to ASD risk may provide new mechanistic insight. We applied a multi-omics Mendelian randomization (MR) framework integrating methylation (mQTL), expression (eQTL; blood and 12 GTEx brain regions), and protein (pQTL) datasets.

We used summary-data-based MR (SMR) with HEIDI to exclude LD-driven signals and Bayesian colocalization (PPH4 > 0.70) to require a shared causal variant. Where independent cis instruments were available, two-sample MR estimated effects and assessed robustness. ASD outcomes came from IEU-802, IEU-806, and FinnGen GWAS. Convergent evidence highlighted three mitochondria-related genes.

CRAT and PRDX6 showed cross-layer support in specific datasets (mQTL/eQTL/pQTL) with overall protective associations. TMEM177 was supported across mQTL and eQTL and exhibited tissue-specific divergence-risk-increasing associations in cerebellar/cortical regions but protective associations in peripheral blood. TMEM177's biology is consistent with a role in complex IV (COX2) assembly, CRAT regulates acetyl-CoA buffering and metabolic flexibility, and PRDX6 contributes to redox homeostasis and membrane repair. Locus-specific CpG variation was directionally aligned with gene expression and ASD risk.

Our findings support a structure-metabolism-redox axis-TMEM177, CRAT, and PRDX6-linking mitochondrial regulation to ASD susceptibility.