The impact of each individual parameter on morbidity and mortality of COVID-19 is consistent with the physiology of this primary hemostasis system and very much in line with the pathophysiology of thrombotic microangiopathy: The excess of VWF, the decrease of ADAMTS13, the occurrence and the concentration of antibodies to ADAMTS13: Each of these individual parameters independently predicts adverse outcome. The gene discussed is ADAMTS13; the disease is Genetic thrombotic microangiopathy.