present after discontinuation of eculizumab treatment and close monitoring is required. epidemiology ahus can be inherited or acquired, and does not appear to vary by race, gender, or geographic area. as expected with an ultra-rare disease, data on the prevalence of ahus are extremely limited. a pediatric prevalence of 3.3 cases per million population is documented in one publication of a european hemolytic uremic syndrome (hus) registry involving 167 pediatric patients. society and culture naming atypical hemolytic uremic syndrome (ahus) has also been referred to as diarrhea-negative hemolytic-uremic syndrome (d− hus).: 2170 research directions patient advocacy groups have been helping to determine research priorities.