Vasculitis & polymyalgia rheumatica
Higher Complement C4 Gene Copy Number Constitutes a Shared Genetic Risk Factor for Giant Cell Arteritis and IgA Vasculitis
Main finding · Male patientsResult — go to the resultOdds ratio 1.23 95% CI 1.07–1.42Authors' conclusion
This study reveals sex-dependent variation in C4 CN as a novel genetic risk factor for GCA and IgAV, suggesting shared biologic mechanisms involving complement dysregulation, sustained inflammation, and vascular damage.
Study context
- Population
- Patients with giant cell arteritis (GCA), patients with IgA vasculitis (IgAV), and controls with genotypic data
- Participants
- 3,498 / 284 / 16,867
- Comparison
- Patients with GCA or IgAV vs controls
- GCAn = 3,498
- IgAVn = 284
- Controlsn = 16,867reference
- Outcome
- Association of C4A, C4B and HERV-K copy number (CN) with vasculitis risk, overall and stratified by sex
Methodological detailscopy number imputation from genotypic data, sex-stratified analysis, conditional analyses on classical HLA alleles
- Copy number imputation from genotypic data
- Sex-stratified analysis
- Conditional analyses on classical HLA alleles
Main finding
Male patients
Odds ratio
1.23
95% CI 1.07–1.42
P = 4.52 × 10-3
GCAvs Controls
OR 1.23 (95% CI 1.07–1.42); P = 4.52 × 10-3
As reported in the abstract
Observational data: associations, not effects.
Further findings
| Outcome | OR (95% CI) | P value | |
|---|---|---|---|
| Elevated C4A CN and IgAV susceptibility, overall cohortIgAVvs ControlsPFDR = 4.48 × 10-3 | 1.68 (1.22–2.30) | P = 1.49 × 10-3 | |
| C4B CN and IgAV, male-biased trendIgAVvs ControlsPFDR = 5.80 × 10-2 | 1.46 (1.02–2.08) | P = 3.88 × 10-2 | |
| 0.512Odds ratio (log scale) |
Independence from classical HLA alleles
- Conditional analyses confirmed associations independent of classical HLA alleles
Original publication
Higher Complement C4 Gene Copy Number Constitutes a Shared Genetic Risk Factor for Giant Cell Arteritis and IgA Vasculitis. Arthritis Rheumatol. Published 27 April 2026. doi:10.
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