APP and Alzheimer disease: For example, this CRISPR/Cas9-mediated knock-in could be used to introduce human neurodegenerative disease variants into conserved endogenous killifish loci (e.g. amyloid precursor protein [APP] for Alzheimer’s disease) or to drive neurodegenerative disease variants using a pan-neuronal promoter such as ELAVL3 (though we have not examined how the expression level of ELAVL3 changes with age in this study).