Schizophrenia risk from complex variation of complement component 4.
Level 4 - case-series / case-control
Genetic association analysis combined with postmortem human tissue work and animal mechanistic experiments.
PubMed 26814963 · doi:10.1038/nature16549
What was done
The authors analyzed structural variation in complement component 4 (C4) genes (C4A and C4B) within the major histocompatibility complex (MHC) locus in relation to schizophrenia risk. They evaluated how these alleles correlate with C4A and C4B expression in human brain tissue, mapped human C4 protein localization in neurons, and investigated C4's role in postnatal synapse elimination in mouse models.
What was found
The abstract reports no numerical values, sample sizes, effect sizes, or confidence intervals. Structurally diverse C4 alleles generated varying levels of C4A and C4B expression in the brain, with schizophrenia risk associating in proportion to increased C4A expression. Human C4 protein localized to neuronal synapses, dendrites, axons, and cell bodies, and C4 mediated postnatal synapse elimination in mice.
Why it matters
This work links the longstanding MHC genetic association in schizophrenia to specific C4 structural variants, offering a biological mechanism whereby elevated complement activity drives synaptic pruning during development.
Limits
The abstract provides no sample sizes, numerical effect sizes, or statistical metrics for the human genetic datasets, postmortem samples, or mouse experiments. Functional synaptic elimination findings are derived from animal models rather than directly observed in living humans.
Cited by
- supports The complement pathway is involved in synapse formation and synaptic remodeling.