Resistance to activated protein C (APCR) in children with acute lymphoblastic leukaemia—the need for a prospective multicentre study

Activated protein C resistance (APCR), usually due to the Arg506→Gln point mutation of the factor V gene, has emerged as the most important hereditary cause of venous thromboembolism. Using an aPTT based method in the presence of APC, together with a DNA technique based on the polymerase chain reaction, we investigated 65 leukaemic children and 65 age-matched healthy controls for the presence of this mutation. In both groups three children showed APCR, All six children showed the common factor V gene mutation, Arg506→Gln. Although no child in the control group presented with thrombosis, all three children with acute lymphoblastic leukaemia had thromboembolic events. Whether the poor anticoagulant response to activated protein C in leukaemic children treated with prednisone, vincristine, daunorubicin and asparaginase affects the risk of thrombotic events requires a more extensive multicentre study.