The dual complication of myocardial infarction and sepsis in patients with ET is extremely rare, and this case has the following implications: Unexplained thrombocytosis (platelet count > 450 × 109/L), even in the absence of a history of MPNs, requires JAK2 gene testing according to ICC guidelines; Thrombosis and sepsis crises can occur simultaneously in patients with ET. The gene discussed is JAK2; the disease is deep vein thrombosis.