PSEN1 and Alzheimer disease: These transgenic mice overexpress chimeric mouse/human APP (Mo/HuAPP695swe) and a mutant human presenilin 1 (PS1‐ΔE9), both transgenes driven by independent prion promoters [43] Because this transgenic line starts depositing plaques as early as six months and starts secreting Aβ within 3–4 months [46], this mouse line is a good model of early‐onset AD.