CFHR1 and IgA glomerulonephritis: In addition, homozygous deletion of FHR1, which is a common copy number variation, associates with lower risk of certain complement-mediated diseases including AMD, C3G, aHUS, and IgA nephropathy (109–111), while increased levels of FHR1 are seen in C3G and IgA nephropathy (63, 112).