APOE and early-onset autosomal dominant Alzheimer disease: (2) Methods: A literature search was performed combining the following Medical Subject Heading (MeSH) terms on PubMed: “Alzheimer’s disease”, “biomarkers”, “APOE”, “APP”, “GWAS”, “cerebrospinal fluid”, “polygenic risk score”, “Aβ42”, “τP-181”, “ p-tau217”, “ptau231”, “proteomics”, “total tau protein”, and “precision medicine” using Boolean operators.