Common genetic variants in complement genes other than CFH, CD46 and the CFHRs are not associated with aHUS

It is well established that common genetic variants in CFH, CD46 and the CFHRs are additional risk factors for the development of aHUS. To examine the hypothesis that common variants in other complement genes have a similar effect we genotyped 501 SNPs in 47 complement genes in 94 aHUS patients from Newcastle, 126 aHUS patients from Paris, 374 UK controls and 165 French controls. We replicated the associations in CFH, CD46 and the CFHRs but found no association with any other complement gene. The strongest associations replicated in both cohorts were found for four SNPs within CD46 (p-value < 10−3) and five SNPs within CFH (p-value <5 × 10−3). Significant replicable associations with single SNPs in CFHR2, CFHR4 and an intergenic SNP (CR1-CD46) were also found. Analysis of the Paris cohort showed that the association with CD46 SNPs was only present in those patients with complement mutations. Haplotype analysis showed at-risk and protective haplotypes in both CD46 and CFH. The CD46 haplotype was only disease-associated in those patients with mutations.

► Hypothesis tested: common sequence variants in complement are associated with aHUS. ► SNPs in complement genes were genotyped in two independent aHUS cohorts. ► Only SNPs within CFH, CD46 and the CFHRs showed a replicable association with aHUS. ► Complement regulators variability has the main role in determining the disease.