RESISTANCE TO ACTIVATED PROTEIN-C (APCR) IN CHILDREN WITH ACUTE LYMPHOBLASTIC-LEUKEMIA - THE NEED FOR A PROSPECTIVE MULTICENTER STUDY

Activated protein C resistance (APCR), usually due to the Arg506 --> G ln point mutation of the factor V gene, has emerged as the most import ant hereditary cause of venous thromboembolism. Using an aPTT based me thod in the presence of APC, together with a DNA technique based on th e 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 co mmon 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 a nticoagulant response to activated protein C in leukaemic children tre ated with prednisone, vincristine, daunorubicin and asparaginase affec ts the risk of thrombotic events requires a more extensive multicentre study.