CFH and age-related macular degeneration: Interestingly, ~30% of individuals of European descent carry at least one copy of the Y402H risk allele.27 Two studies tested SNPs within target regions of chromosome 1q, previously indicated by linkage analysis studies, for AMD association using case–control populations.23,25 In another, Hageman et al.24 examined SNPs within the candidate CFH gene; they had previously implicated complement activation in AMD pathogenesis.22 The most noteworthy of the studies, the GWAS by Klein et al.7, examined more than 100,000 SNPs across the whole genome within 96 cases and 50 controls.