 Recently it was discovered that about 35% of individuals carry an at-risk Single Nucleotide Polymorphism in one or both copies of their factor H gene.Homozygous individuals have an approximately sevenfold increased chance of developing age-related macular degeneration, while heterozygotes have a two-to-threefold increased likelihood of developing the disease.This SNP, located in CCP module 7 of factor H, has been shown to affect the interaction between factor H and heparin indicating a causal relationship between the SNP and disease.