Transgenic animal models of AD such as the double transgenic mice expressing a chimeric mouse/human amyloid precursor protein (Mo/HuAPP695swe) and a mutant human presenilin 1 (PS1-dE9) (APP/PS1) mice, have dysbiosis, with increased relative abundance of B. subtilis (Bacillus subtilis) and E. coli (Escherichia coli) (Harach et al., 2017), large producers of Aβ. This evidence concerns the gene PSEN1 and Alzheimer disease.