Abstract: Objective? To analyze the clinical characteristics of atypical hemolytic uremic syndrome (aHUS) caused by CFHR family gene variation in a child. Methods? The clinical data and the results of related gene mutation analysis by second-generation sequencing technology were retrospectively analyzed in a child with aHUS. Results? The 8 -year-old girl presented with ochriasis and had hematuria after respiratory infection. Laboratory examination showed hemolytic anemia, thrombocytopenia, acute kidney injury and decrease in complement C 3 . No abnormalities were found in complement C 4 . Renal pathology showed thrombotic microangiopathy. The child was clinically diagnosed with aHUS. Gene analysis showed homozygous deletion of CFHR1 and CFHR3 genes and a heterozygous indel mutation (c.333_3del, p.1112Ffs*18 ) in CFHR2 genes. Genetic analysis of the mother and brother revealed the same results as those in the child, and the father only had homozygous deletion of CFHR1 and CFHR3 genes. The parents are not consanguineous. Hematuria related screening results of parents and younger brother were normal. Conclusion? A case of childhood aHUS caused by homozygous deletion of CFHR1 and CFHR3 and a heterozygous deletion of CFHR2 is reported for the first time.

Key words: child;? atypical hemolytic uremic syndrome;? CFHR gene;? compound deletion mutation