If a dad or mum on the proband is thought to hold the pathogenic variant identified within the proband, the chance into the sibs of inheriting the pathogenic variant is 50%. Thanks to lowered penetrance, sibs who inherit the pathogenic variant might or might not produce aHUS (see Penetrance). As https://donovanmrvad.blogdigy.com/the-fact-about-air-handling-units-ahus-that-no-one-is-suggesting-47581662