CFHR1 and IgA glomerulonephritis: High frequencies of homozygous CFHR3–CFHR1 deletion have been reported in aHUS patients with anti-FH autoantibodies or with mutations in complement factor I (22), as well as in Middle Eastern and North African control populations (23, 24); the reason for the high frequency of the homozygous CFHR3-CFHR1 deletion in certain control populations could be related with its protective role against age-related macular degeneration (25) and IgA nephropathy (26).