An exTREMe disruption in Alzheimer's cleanup.

Partial loss-of-function variants in the TREM2 immune receptor are associated with increased risk for Alzheimer's disease (AD) and other forms of neurodegenerative disease, but the molecular bases for these connections are unknown. Three new structures of WT and R47H mutant TREM2 immunoglobulin-like (Ig-like) domain now reveal that R47 functions to correctly position elements of the ligand-binding surface. Intriguingly, the authors also demonstrate a disruption of receptor oligomerization by the R47H mutation, suggesting a role for ligand-induced clustering in receptor signaling and resultant plaque clearance.