APP and Alzheimer disease: In addition, they observed a correlation between the relative abundance of bacterial genera and the levels of cerebrospinal fluid biomarkers of AD [16]. According to Bäuerl et al., a transgenic APP/PS1 (Tg) mouse model was also successful in showing how AD pathology shifted gut bacterial profiles in favor of Proteobacteria and Erysipelotrichaceae, which potentially contributed to disease progression and severity [17].