C1QA
Complement C1q subunit A
Also known as: C1QA, C1q
Biology & Mechanism
C1QA encodes a subunit of the C1q complement complex, which is produced by microglia and tags synapses for elimination during development and disease. In Alzheimer's disease and aging, excessive C1q-mediated synaptic tagging followed by microglial phagocytosis contributes to synapse loss. C1q is markedly upregulated in the aging and diseased brain. Blocking C1q has been shown to reduce synapse loss in disease models.
Open Questions
- —At what stage of neurodegeneration does C1q-mediated synapse elimination become detrimental rather than protective?
- —Can C1q blockade be applied selectively to the CNS without compromising systemic complement immunity?
- —What is the relationship between C1q upregulation and tau pathology?
Sources
- Complement and microglia mediate early synapse loss in Alzheimer mouse models (2016)
Last reviewed: June 1, 2026