This in turn could facilitate the local seeding and spreading of tau,54 findings which were also reported in the AD patient brain where a reduced microglial accumulation around plaques associated with higher pathological tau burden was found in TREM2 R47H HD patients.55 However, it still remains unclear as to why TREM2 seems to influence only cognition and not motor decline in our HD study, but it could relate to an effect it may have on the distribution of pathology. The gene discussed is TREM2; the disease is Alzheimer disease.