aHUS (atypical haemolytic uremic syndrome) is an ultra rare (less than 20 cases per million population) human disease. A laymans perspective is available from Atypical HUS Foundation which explains about types of HUS, aHUS treatment with eculizumab etc,.
A non-technical video (36m) ‘The Complement System made simple’ explains complement.
aHUS may be of use in understanding Alabama Rot – see Laura Holm et al paper.