Two patients were diagnosed as having a complement dysregulation HUS: one patient with a complete homozygous deletion of complement factor H-related protein 1 (CFHR1) and complement factor H-related protein 3 (CFHR3), who had anti-factor H antibodies production, and one patient with a likely homozygous pathogenic variant in C3 gene. This evidence concerns the gene C3 and hemolytic-uremic syndrome.