Dementia in older adults is clinically, genetically and pathologically heterogeneous. Understanding this heterogeneity and addressing all the biological pathways that increase risk and lower resilience, will be required to provide precision prevention, diagnosis and treatment. Genome wide association studies (GWAS) have implicated over 40 genes, multiple cell and varied biological pathways (amyloid, tau, endolysosomal, mitochondrial function, inflammation). Genetic and multiomic characterization of ADRD in individuals, and in groups of patients, could exploit this heterogeneity towards more effective, precise, personalized prevention and treatment of dementia. Whereas, most of these biological discoveries have been in non-Hispanic whites, there is a paucity of data on Mexican American (MA) Hispanics, who are the fastest growing segment of older adults in the US. The Genetics and Multiomics Core (GMC) of the South Texas Alzheimer Disease Consortium (STAC) has the following specific aims: Aim 1: Identifying causal genetic variation underlying ADRD in CC enrollees through a combination of routine clinical sequencing and a ‘Undiagnosed Disease Network’ approach to identifying novel genetic variation that may be causal or contributory. To achieve this, we will record results of clinical sequencing and genetic counseling in proband and relatives. Aim 2: Genetically characterize all CC enrollees (using APOE and GWAS) to expand our understanding of genetic variation modifying risk, resilience and disease progression. We will aim to refine and improve genetic risk estimates for late onset AD, PD, DLB permitting more accurate risk stratification in MA Hispanics, better targeting for recruitment in clinical trials. Aim 3: Serve as a resource for STAC investigators, trainees, and the national ADRD research community for deeply phenotyped Hispanic MA samples, genomic data and innovative analysis methods. To achieve this (i) GMC will share DNA, genetic and phenotypic data (clinical, MRI and PET imaging, blood and CSF -amyloid, tau, inflammation, metabolomic, lipidomic- and sensory-motor biomarkers) and digital and conventional neuropathology, through NCRAD, NIAGADS, NACC; (ii) GMC will serve as a STAC resource for providing methylation, transcriptomics (blood, brain, CSF), ATAC-Seq, single-cell omics data and for generating usable iPSCs and organoids; (iii) GMC will develop and share innovative genetic and multiomic association analyses methods, especially for use in large families; (iv) GMC will facilitate collaborations with consortia such as the Alzheimer Disease Genetics Consortium (ADGC), the International Genomics of AD Project (IGAP), Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) and Transomics in Precision Medicine (TOPMed); (v) GMC faculty and resources will support the Research Education Core in developing a diverse workforce, well-trained in applying genetic and multiomic research methods.