C3 and COVID-19: Furthermore, common polymorphisms in thrombotic microangiopathy-associated genes such as the rs2230199 in C3, the rs800292 in CFH (26 patients), and the rs2301612 missense mutation (448E) in the gene itself ADAMTS13, reported in 60 patients with moderate-to-severe COVID-19 studied by Graviilaki E. et al., may contribute to penetrance modulation [22].