Clinical and genetic characteristics of patients diagnosed with atypical hemolytic uremic syndrome (aHUS): epidemiological data from the Belgian cohort of the Global aHUS Registry.

[en] BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) usually results from an overactivation of the alternative complement pathway. As large clinical trials are scarce, patient registries can partially fill the knowledge gap on patient characteristics, management, and outcomes. We here describe the baseline clinical and genetic characteristics as well as the management of all Belgian patients enrolled in the Global aHUS Registry at data cut-off.
METHODS: This observational study prospectively and retrospectively collected data (data cut-off: December 26, 2022) from patients of all ages with a clinical diagnosis of aHUS, irrespective of treatment.
RESULTS: A total of 121 Belgian patients were registered in the Global aHUS Registry, resulting in a prevalence of 10.4 aHUS patients per million inhabitants, with a higher proportion of females affected (57.9% vs 42.1% of males). Among the 109 patients tested for at least one variant and/or anti-complement factor H (CFH) antibodies, 36 were positive for a pathogenic complement gene variant associated with aHUS (n = 29) and/or seropositive for anti-CFH antibodies (n = 14). The most common variants affected CFH, C3 and CD46. The higher proportion of complement gene variants in treated women versus men was not related to a specific gene.
CONCLUSIONS: This study strengthens the real-world evidence on aHUS and adds to previously published Global aHUS Registry data. In addition, it provides insights into the differential epidemiology of the disease in Belgium and demonstrates the increased susceptibility of women to aHUS across the whole spectrum of recognized complement gene variants.