This hypothesis is supported by the finding that bacteria belonging mainly to the Enterobacteriaceae family, including Escherichia coli, Pasteurellaceae genera, including Haemophilus influenzae, and Lactobacillaceae family bearing the GGTA1 gene [20] have been found post-mortem in the brain of AD and control subjects and all contribute to the brain microbiome [21]. The gene discussed is GGTA1; the disease is Alzheimer disease.