Activated Protein C Resistance in Polycythemia Vera

Area of Science:

• Hematology
• Thrombosis Research
• Molecular Genetics

Background:

• Activated protein C resistance (APC-R), often due to Factor V Leiden mutation, is a known thrombosis risk factor.
• Polycythemia vera (PV) is associated with a hypercoagulable state and increased thromboembolic risk.
• The specific role of APC-R in PV-related thrombosis requires further investigation.

Purpose of the Study:

• To evaluate the prevalence and impact of APC-R in patients with polycythemia vera.
• To compare APC-R and thrombosis risk in PV patients versus chronic myelogenous leukemia (CML) patients and healthy controls.
• To determine if APC-R is an independent risk factor for thrombosis in PV.

Main Methods:

• Assessed APC-R using an aPTT-based test.
• Measured Factor VIII activity and anticardiolipin antibodies (IgG and IgM) via ELISA.
• Identified Factor V Leiden mutation using polymerase chain reaction.
• Compared data from PV patients (n=24), CML patients (n=27), and healthy controls (n=52).

Main Results:

• APC-R was found in 20.8% of PV patients and 14.8% of CML patients, significantly higher than healthy controls (1.8%).
• Thrombosis risk in PV patients was independent of APC-R presence.
• Factor V Leiden mutation was rare, identified in only one CML patient with APC-R but no thrombosis.

Conclusions:

• While APC-R is more prevalent in PV and CML patients, it does not appear to be a major driver of thromboembolic complications in PV.
• Thrombosis in PV likely results from other factors within the disease's hypercoagulable state.
• Further research into PV-specific thrombotic mechanisms is warranted.