Therefore, it is important to investigate all patients presenting with SVT without attributable local pathology, such as malignancy, sepsis or pancreatitis, for the presence of JAK2 V617F mutation, which is present in 80–90% of patients with MPN‐SVT (Kiladjian et al, 2008), and if this is negative, testing should be done for a CALR mutation, which is present in about 2·5% (Sekhar et al, 2016). The gene discussed is CALR; the disease is myeloproliferative neoplasm.