FH and autoimmune disease: Also, it is possible that only certain subgroups of the population are at increased risk of developing anti-FH related autoimmune diseases, such as persons with preexisting autoimmune diseases or healthy persons with a deficiency of complement factor H (CFH)-related proteins such as occurs in ∼ 6% of the population (37), and are associated with autoantibodies to FH and aHUS (24, 26, 38, 39).