Assessment of common genetic variation in Alzheimer’s and Parkinson’s diseases reveals global distinction in population attributable risk

Emerging evidence suggests that the genetic architecture of Alzheimer’s (AD) and Parkinson’s diseases (PD) risk varies across ancestries. This study seeks to explore distinct and universal genetic targets across individuals of Latino, African/African Admixed, East Asian, and European populations by implementing Population Attributable Risk (PAR) comparisons on summary statistics from genome-wide association studies (GWAS). PAR was calculated for the most significant disease variants using summary statistics derived from select multi-ancestry GWAS meta-analyses, followed by fine-mapping analysis to validate genetic contribution of disease variants to European, African/African Admixed, East Asian, and Latino individuals. For both AD, APOE4 PAR estimates were universally high across all ancestries, with TSPAN14 and PICALM emerging as other common targets. Attributable risk varied across PD-related major risk loci including variation nearby GBA1 and LRRK2 . In contrast, SNCA, MCCC1, VPS13C , and MAPT loci demonstrated comparable attributable risk across ancestries. This cross-ancestry evaluation of PAR reinforces the genetic heterogeneity of AD and PD. In consideration of the complex etiology of these diseases, these findings may inform the strategic prioritization of therapeutic targets and improve global health outcomes.