What is the pathway that is dysregulated in atypical HUS (aHUS)?
The alternative pathway of the complement system is dysregulated in aHUS. In a steady state the alternative pathway is always active.
There is continuous production of C3b from C3 (called “C3 tickover”). C3b deposition in tissues leads to formation of the C5b-9 terminal complement complex, which in turn leads to injury of normal cells.
In atypical HUS the alternative pathway is dysregulated, leading to increased C3b production.
This allows for increased terminal complement complex and thereby cell injury.
