A multi-omics study on monozygotic twins discordant for amyotrophic lateral sclerosis and literature review underline a potential role for innate immunity and epigenetic dysregulation in disease mechanisms.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by motor neuron degeneration. Although genetic contributions to both familial and sporadic ALS (sALS) cases are well established, a substantial portion of ALS heritability remains unexplained, suggesting the involvement of other genetic and epigenetic factors. METHODS: To address this gap, we have devised a comprehensive multi-omics approach in a pair of Italian monozygotic twins discordant for ALS, performing DNA methylation, transcriptomic, and whole exome sequencing (WES). We then conducted a structured literature research on ALS-discordant monozygotic twins (n = 45) and on case-control sALS (~ 7000 patients and ~ 3000 controls), investigated for at least one of the omics approaches. RESULTS: Our exploratory analysis reveals distinct transcriptomic and epigenetic profiles underlying the discordant disease phenotypes in genetically identical individuals, particularly implicating immune system functions and brain development pathways. Notably, a comprehensive comparison of our results with existing literature underlined the involvement of pathways related to NK cell activation, chemokine production, and signal transduction, suggesting potential shared disease associated mechanisms across ALS cases. CONCLUSIONS: This hypothesis-generating study, although limited by the sample size, demonstrates the utility of multi-omics approaches in uncovering broader pathological insights into ALS, speculating on the possible contribution of innate immunity and epigenetic dysregulation in disease processes. This work provides a foundation for future research aimed at identifying disease-associated processes and biomarkers.