Genetic atypical hemolytic uremic syndrome in children: a 20-year experience from a tertiary center

• Published in: Brazilian Journal of Nephrology 2021-01, Vol.43 (3), p.311-317
• Main Authors: Maximiano, Cristiana, Silva, Andreia, Duro, Inês, Branco, Tiago, Correia-Costa, Liane, Teixeira, Ana, Rocha, Liliana, Costa, Teresa, Matos, Paula, Faria, Maria do Sameiro, Mota, Conceição, Afonso, Alberto Caldas
• Format: Article
• Language: English
• Subjects: Atypical Hemolytic Uremic Syndrome; Child; Genetic Testing; Original; Thrombotic Microangiopathies
• ISSN: 0101-2800; 2175-8239
• DOI: 10.1590/2175-8239-JBN-2020-0199

Abstract Introduction: Atypical hemolytic uremic syndrome (aHUS) is a rare disorder characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, which primarily affects preschool-aged children. This study’s aim was to describe the clinical profile, management, and long-term outcome of the genetic aHUS patients admitted to a tertiary care pediatric nephrology center during 20 years. Methods: We performed a retrospective analysis of the clinical records of all aHUS patients younger than 18 years with identified genetic mutations. Data on clinical features, genetic study, therapeutic interventions, and long-term outcomes were reviewed. Results: Five cases of aHUS with an identified genetic mutation were included; all were inaugural cases with the youngest being 4 months old. Complement factor H gene mutation was identified in four patients. Therapeutic plasma exchange was performed for acute management in 4 patients, one of whom also needed acute renal replacement therapy (peritoneal dialysis). All patients went on complete remission, 2 had more than one relapse but only 1 of these progressed to chronic kidney disease during the follow-up period (median (25th-75th percentile), 136 (43.5-200.5) months). Conclusion: In children, the prognosis of renal function seems to be strongly dependent on the genetic background, thus being crucial to perform genetic study in all aHUS cases. In our cohort, 2 patients presented genetic mutations not previously described. Recent innovations on the genetic field leading to the identification of new mutations has lead to a better understanding of aHUS pathogenesis, but further studies, focusing on the genotype-phenotype correlation, with longer follow-up periods, are needed.