If a father or mother of the proband is known to have the pathogenic variant discovered during the proband, the chance to your sibs of inheriting the pathogenic variant is 50%. As a result of diminished penetrance, sibs who inherit the pathogenic variant may or may not acquire aHUS (see https://donovanwsldt.digitollblog.com/32652359/top-latest-five-air-handling-unit-ahu-hire-urban-news