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Objective:To summarize and analyze the clinical phenotype and genotype characteristics of atypical hemolytic uremic syndrome (aHUS) in Chinese children.Methods:It was a retrospective study. The clinical data and genetic results of 6 children with aHUS admitted to Children's Hospital Affiliated to Capital Institute of Pediatrics from May 2016 to October 2022 were analyzed, and literature on Chinese aHUS children with genetic screening data by searching databases such as Wanfang, CNKI, and PubMed were reviewed and summarized. Through literature search, the children with aHUS were divided into genetic variation group and non-genetic variation group according to the results of genetic testing, and the differences of clinical phenotype, laboratory examination, follow-up and outcomes were compared between the two groups. Logistic regression method was used to analyze the risk difference of disease recurrence, end-stage kidney disease and death between genetic variation group and non-genetic variation group.Results:Among the 6 aHUS children in this center, there were 1 male and 5 females, with onset age of 7 months to 10 years old. Four patients had gene variations, including 1 patient of complement factor H ( CFH) gene variation, 1 patient of C3 gene variation, and 2 patients of CFHR1 combined with CFHR3 gene variation. Six children had gross hematuria, proteinuria, hypertension and decreased complement C3. The mean values of serum creatinine in 4 genetic variation and 2 non-genetic variation children were 153.9 μmol/L and 214.3 μmol/L, respectively; the mean values of estimated glomerular filtration rate were 26.4 ml·min -1·(1.73 m 2) -1 and 28.9 ml·min -1·(1.73 m 2) -1, respectively; the mean values of hemoglobin were 81 g/L and 57 g/L; the mean values of platelet were 46×10 9/L and 71×10 9/L; the mean values of lactic dehydrogenase were 2 408 U/L and 2 106 U/L, respectively; there were 1 and 2 cases of positive CFH antibody, and 1 and 1 case of nervous system complication, respectively. Ninety-seven aHUS children were retrieved including the reported 6 cases in this center, with 60 males and 37 females, and median onset age of 5 years old. The positive detection rate of genetic variation was 58.8% (57/97). The main type of genetic variation was CFHR gene variation (43.9%, 25/57), followed by CFH gene variation (33.3%, 19/57).There was no significant difference in onset age, sex distribution, proportions of gross hematuria, massive proteinuria, hypertension, complement C3 decline, positive CFH antibody and treatment method, platelet, and lactic dehydrogenase between genetic variation group and non-genetic variation group (all P>0.05). Compared with the genetic variation group, non-genetic variation group had higher serum creatinine ( Z=2.311, P=0.021) and lower hemoglobin ( Z=-2.636, P=0.008). The median follow-up time in genetic variation group and non-genetic variation group was 1 year and 2 years, respectively. The proportions of non-remission and recurrence in the genetic variation group were significantly higher than those in non-genetic variation group ( χ2=12.016, P=0.002; χ2=4.689, P=0.030). Logistic regression analysis showed that the recurrence risk of aHUS in children with genetic mutations was higher than that in children with non-genetic mutations ( OR=2.807, 95% CI 1.014-7.772). Conclusions:The main type of aHUS gene variation in Chinese children is CFHR gene variation, and the children with gene variation have poor prognosis and a higher risk of recurrence.