P. gingivalis specific cell free DNA can be detected in the cerebrospinal fluid and its protease virulence factors, arginine-gingipain (Rgp) and lysine-gingipain (Kgp), are present in the brains of over 90% of AD patients and correlate with tau and ubiquitin pathology [1]. The gene discussed is MAPT; the disease is Alzheimer disease.