Do all mutations in the genes regulating the complement pathway cause phenotypic disease of atypical HUS (i.e., penetrance)?
No. The majority of complement mutations associated with aHUS are heterozygous with many family members remaining asymptomatic. Penetrance of hereditary aHUS is estimated to be 50% in carriers.
This suggests that both genetic and environmental insults are required for disease expression of atypical HUS.
