Acknowledging that HCM has been previously reported in rare instances of CML and MPN (Khoury et al., 2012[3]; Toro-Tobón et al., 2017[4]), the rationale for reflexive screening of the BCR-ABL1 and JAK2 V617F rearrangements in patients presenting with hypercalcaemia without other evidence of an MPN is unfounded. The gene discussed is JAK2; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.