Might be involved in complement regulation. Expressed by the liver and secreted in plasma. Disease susceptibility is associated with variants affecting the gene represented in this entry. A deletion encompassing CFHR1 and CFHR3 is associated with an increased risk of atypical hemolytic uremic syndrome, likely due to a defective regulation of complement activation (PubMed:17367211). Some patients carrying the deletion have serum anti-CFH autoantibodies (PubMed:18006700).