Heritability Enrichment Implicates Microglia in Parkinson's Disease Pathogenesis

Area of Science:

• Neuroimmunology
• Genetics
• Parkinson's Disease Research

Background:

• Understanding the immune system's role in Parkinson's disease (PD) pathogenesis is crucial for developing effective therapies.
• Investigating the genetic underpinnings of PD, particularly the contribution of immune cell types, remains a significant challenge.

Purpose of the Study:

• To investigate the enrichment of common variant heritability for Parkinson's disease (PD) stratified by immune and brain cell types.
• To identify specific immune cell populations and genetic loci involved in PD pathogenesis.

Main Methods:

• Utilized summary statistics from genome-wide association studies (GWAS) for Parkinson's disease.
• Applied linkage disequilibrium (LD) score regression to partition heritability across cell-type-specific open chromatin regions.
• Validated findings using polygenic risk score (PRS) analysis and intersected genetic data with epigenetic and expression quantitative trait loci (eQTL) data.

Main Results:

• Significant enrichment of PD risk heritability was observed in open chromatin regions of microglia and monocytes.
• The enrichment signal for microglia remained significant in a joint model, indicating a primary role.
• Identified P2RY12, a microglial gene targeted by clopidogrel, as a likely driver of a significant PD association on chromosome 3.

Conclusions:

• Immune mechanisms, particularly microglial dysregulation, are critical etiological factors in Parkinson's disease pathogenesis.
• The study nominates P2RY12 as a targetable microglial gene candidate involved in PD.
• Modulating immune processes presents a promising therapeutic avenue for future Parkinson's disease treatments.