This page provides a comprehensive reference for gene expression patterns in the brain across neurodegenerative diseases, leveraging data from the Allen Brain Atlas and other comprehensive expression studies. Understanding where genes are expressed in the brain is fundamental to interpreting GWAS findings, identifying cell-type-specific vulnerability, and developing targeted therapies. [@allen2024]
Gene expression patterns reveal which cell types express disease-relevant genes, providing insights into mechanism and potential therapeutic windows. Single-cell RNA sequencing has revolutionized our understanding of cell-type-specific expression in neurodegenerative diseases. [@seaad2023]
This page provides a comprehensive reference for gene expression patterns in the brain across neurodegenerative diseases, leveraging data from the Allen Brain Atlas and other comprehensive expression studies. Understanding where genes are expressed in the brain is fundamental to interpreting GWAS findings, identifying cell-type-specific vulnerability, and developing targeted therapies. [@allen2024]
Gene expression patterns reveal which cell types express disease-relevant genes, providing insights into mechanism and potential therapeutic windows. Single-cell RNA sequencing has revolutionized our understanding of cell-type-specific expression in neurodegenerative diseases. [@seaad2023]
--- [@brain2021]
Brain Region Expression Patterns
Alzheimer Disease Expression Signatures
Hippocampal Expression: The [hippocampus](/brain-regions/hippocampus) shows early involvement in AD. Key genes with hippocampal expression include: [@gtex2020]
[APP](/entities/app-protein): High expression in pyramidal [neurons](/entities/neurons), moderate in interneurons
[MAPT](/proteins/tau) (Tau): High expression in pyramidal neurons; isoform expression shifts in AD
[APOE](/proteins/apoe): Expressed in [astrocytes](/entities/astrocytes) and [microglia](/cell-types/microglia-neuroinflammation); APOE4 carriers show altered expression
[TREM2](/proteins/trem2): Microglia-specific expression; expression increases in AD
[Entorhinal Cortex](/brain-regions/entorhinal-cortex) Expression: The entorhinal [cortex](/brain-regions/cortex) is the earliest affected region: [@eqtl2022]
SNCA: Low baseline expression but increases with pathology
GRN: High expression in microglia; progranulin deficiency leads to [TDP-43](/mechanisms/tdp-43-proteinopathy) pathology
[C9orf72](/entities/c9orf72): Moderate neuronal expression; hexanucleotide expansions cause toxicity
Cortical Expression: Neocortex shows later involvement:
NEFL, NEFM (Neurofilament): Released in neurodegeneration; biomarkers
CLU (Clusterin): Astrocyte expression; clearance of debris
Parkinson Disease Expression Signatures
Substantia Nigra Expression: The substantia nigra pars compacta is selectively vulnerable:
SNCA: High expression in dopaminergic neurons; aggregation triggers cell death
LRRK2: Neuronal expression; kinase activity increases in disease
PARKIN: Ubiquitous but essential in dopaminergic neurons
PINK1: Mitochondrial expression; loss leads to mitophagy defects