Genetic risk for neurodegenerative conditions is linked to disease-specific microglial pathways

Abstract

Genome-wide association studies have identified thousands of common variants associated with an increased risk of neurodegenerative disorders. However, the noncoding localization of these variants has made the assignment of target genes for brain cell types challenging. Genomic approaches that infer chromosomal 3D architecture can link noncoding risk variants and distal gene regulatory elements such as enhancers to gene promoters. By using enhancer-to-promoter interactome maps for microglia, neurons, and oligodendrocytes, we identified cell-type-specific enrichment of genetic heritability for brain disorders through stratified linkage disequilibrium score regression. Our analysis suggests that genetic heritability for multiple neurodegenerative disorders is enriched at microglial chromatin contact sites. Through Hi-C coupled multimarker analysis of genomic annotation (H-MAGMA) we identified disease risk genes for Alzheimers disease, Parkinsons disease, multiple sclerosis and amyotrophic lateral sclerosis. We found that disease-risk genes were overrepresented in microglia compared to other brain cell types across neurodegenerative conditions. Notably, the microglial risk genes and pathways identified were largely specific to each disease. Our findings reinforce microglia as an important, genetically informed cell type for therapeutic interventions in neurodegenerative conditions and highlight potentially targetable disease-relevant pathways.