However, several conditions can produce a clinically similar pseudo-TMA picture, among which severe vitamin B12 deficiency is an underrecognized and potentially treatable mimic that occurs due to ineffective intramedullary erythropoiesis, megaloblastic fragmentation of structurally abnormal erythrocytes, and pancytopenia in the absence of true endothelial injury or ADAMTS13 deficiency. The gene discussed is ADAMTS13; the disease is hyperinsulinemic hypoglycemia, familial, 4.