If a dad or mum in the proband is thought to provide the pathogenic variant discovered during the proband, the chance for the sibs of inheriting the pathogenic variant is 50%. As a consequence of minimized penetrance, sibs who inherit the pathogenic variant may or may not acquire aHUS (see https://ahuhire20753.targetblogs.com/32512398/the-5-second-trick-for-ahu-hire