CALR and myeloproliferative disorder: In a retrospective study on 524 patients with suspected MPN our research group confirmed the diagnostic significance of CALR mutations in the diagnosis of MPN, however, it seemed that the testing for the presence of CALR mutations should only be performed in patients with clear clinical and/or laboratory suspicion for MPN as in other patients CALR mutations may be atypical with an unknown clinical significance [27].