{{Rsnum
|rsid=7951
|Gene=C3
|Chromosome=19
|position=6681980
|Orientation=minus
|ReferenceAllele=C
|GMAF=0.08678
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
|Gene_s=C3
}}{{ population diversity
| geno1=(C;C)
| geno2=(C;T)
| geno3=(T;T)
| CEU | 93.8 | 4.7 | 1.6
| HCB | 91.1 | 8.9 | 0.0
| JPT | 82.1 | 7.7 | 10.3
| YRI | 0.0 | 0.0 | 0.0
| ASW | 0.0 | 0.0 | 0.0
| CHB | 91.1 | 8.9 | 0.0
| CHD | 0.0 | 0.0 | 0.0
| GIH | 0.0 | 0.0 | 0.0
| LWK | 0.0 | 0.0 | 0.0
| MEX | 0.0 | 0.0 | 0.0
| MKK | 0.0 | 0.0 | 0.0
| TSI | 0.0 | 0.0 | 0.0
| HapMapRevision=28
}}
In ~500 Japanese SLE patients, the (T) allele of [[rs7951]], a SNP in the [[C3]] gene, is associated with higher risk for systemic [[lupus]] erythematosus (SLE). The odds ratio is 1.40 (CI: 1.05-1.86, p=0.016). The mean serum level of the C3 protein was lower in (C;T) and (T;T) genotypes than for individuals with (C;C) genotypes.{{PMID|18174230}}

{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}
{{on chip | FTDNA2}}
{{on chip | HumanOmni1Quad}}