The Microglia Genomic Atlas (MiGA) is a genetic and transcriptomic resource comprised of 255 primary human microglia samples isolated ex vivo from four different brain regions of 100 human subjects with neurodegenerative, neurological, or neuropsychiatric disorders, as well as unaffected controls. We performed systematic analyses to investigate sources of microglial heterogeneity, including brain region, age, and sex. We further performed expression and splicing QTL analyses in each region and performed a meta-analysis across the four regions to increase our discovery power. We then performed colocalization and used fine-mapping and microglia-specific epigenomic data to prioritize genes and variants that influence neurological disease susceptibility through gene expression and splicing in microglia. With this approach, we have built the most comprehensive resource to date of cis genetic effects on the microglial transcriptome and propose underlying molecular mechanisms of potentially causal functional variants in several brain disorders.

Human post-mortem brain samples were obtained from the Netherlands Brain Bank (NBB) and the Neuropathology Brain Bank and Research CoRE at Mount Sinai Hospital. The permission to collect human brain material was obtained from the Ethical Committee of the VU University Medical Center, Amsterdam, The Netherlands, and the Mount Sinai Institutional Review Board. For the Netherlands Brain bank, informed consent for autopsy, the use of brain tissue and accompanied clinical information for research purposes was obtained per donor ante-mortem.