PSEN1 and Alzheimer disease: We previously generated knock-in models in zebrafish with each of these types of mutant psen1 allele: K97Gfs, a frameshift mutation encoding a truncated protein similar to the human PS2V isoform that is increased in sporadic, late onset AD [6], and Q96_K97del: an EOfAD-like, reading-frame-preserving deletion of two codons [7].