TREM2 loss-of-function variants impair microglial survival, clustering around amyloid plaques, and phagocytic clearance, creating a non-cell-autonomous amplification loop where dysfunctional microglia accelerate tau pathology. This hypothesis has the strongest human genetic support (R47H OR ~2-4 for AD risk) and active clinical validation through AL002c Phase II trials (TRAILBLAZER-ALZ2). The mechanism is druggable via agonism antibodies, with validated biomarker (sTREM2) for patient stratification. Key uncertainties include timing dependency—TREM2 agonism likely beneficial only in early-mid disease—and species differences in TREM2 signaling. The Skeptic's revised 0.78 confidence captures the modest effect size and bidirectional complexity, while Domain Expert assigns 0.82 reflecting the clinical validation trajectory.
Curated pathway from expert analysis
flowchart TD
A["TREM2 Deficiency<br/>Microglial Lipid Sensing Loss"]
B["DAM Transition Failure<br/>Failed Amyloid Phagocytosis"]
C["Amyloid Plaque<br/>Accumulation"]
D["Plaque-Associated<br/>Neurite Dystrophy"]
E["Synaptic Loss<br/>Cognitive Decline"]
F["TREM2-Deficient Microglia<br/>as Drivers of Toxicity"]
A --> B
B --> C
C --> D
D --> E
A --> F
F --> C
style A fill:#1a237e,stroke:#4fc3f7,color:#4fc3f7
style C fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style E fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9aNo linked papers recorded for this hypothesis yet.
Median TPM across 13 brain regions for TREM2 from GTEx v10.
No clinical trials data linked to this hypothesis yet.
No curated ClinVar variants loaded for this hypothesis.
Run scripts/backfill_clinvar_variants.py to fetch P/LP/VUS variants.
No DepMap CRISPR Chronos data found for TREM2.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
No resource usage or linked notebooks recorded for this hypothesis yet.
| Prediction | Predicted | Observed | Status | Conf |
|---|---|---|---|---|
| IF AL002c (TREM2 agonism antibody) is administered to prodromal-mild AD patients (CDR 0.5-1.0) with elevated amyloid PET for ≥18 months THEN plasma p-tau181 concentration will increase significantly m | ≥30% reduction in plasma p-tau181 annualized rate of change in AL002c-treated group vs. placebo in prodromal-mild AD | — no observation — | pending | 0.74 |
| IF TREM2 agonism enhances microglial amyloid phagocytosis in early-mid AD THEN 18F-flutemetamol PET SUVR will decline significantly faster in the AL002c arm than placebo due to reduced plaque burden, | Significantly greater reduction in cortical amyloid PET SUVR (≥0.05 units) in AL002c-treated early-mid AD patients vs. placebo after 12-18 months of treatment | — no observation — | pending | 0.68 |