Trans-ethnic Genomic Informed Risk Assessment for Alzheimer's disease: An International Hundred K+ Cohorts Consortium Study

Background Alzheimer's disease (AD) is a complex multifactorial progressive dementia affecting all human populations. As a collaboration model between the International Hundred K+ Cohorts Consortium (IHCC) and the Davos Alzheimer Collaborative (DAC), our aim was to develop a trans-ethnic genomic informed risk assessment (GIRA) algorithm for AD. Methods The GIRA model was created to include a polygenic risk score (PRS) calculated from the AD GWAS loci, the APOE haplotypes, and non-genetic covariates including age, sex and first 3 principal components of population substructure. The model was first validated using a dataset from the eMERGE network, and subsequently validated in a South-Asian population in UK and 3 East-Asian populations. The distributions of the PRS scores were also explored in populations from 3 African regions. In two validation sites, the PRS was tested for associated with the levels of plasma proteomics markers. Results We created a trans-ethnic GIRA model for the risk prediction of AD and validated the performance of the GIRA model in different populations. The proteomic study in the participant sites identified proteins related to female infertility and autoimmune thyroiditis and associated with the risk scores of AD, highlighting molecular mechanisms underlying the previously observed correlations between these clinical diseases. Conclusions As the initial effort by the IHCC to leverage existing large scale datasets in a collaborative setting with DAC, we developed a trans-ethnic GIRA on AD with the potential of identifying individuals at high risk of developing AD for future clinical applications. The PRS scores in this model also contribute new research discoveries for the molecular pathogenesis of AD as demonstrated by the proteomic data.