Factor V G1691A Mutation and Factor II G20210A Variant in Children with Venous Thrombosis or Stroke. An International Database Update.

The present database pooling was performed to investigate the clinical phenotype in pediatric factor V G1691A (FV) and factor II G20210A (FII) carriers. 230 pediatric patients with deep venous thrombosis (DVT: n=143) or arterial ischaemic stroke (AIS: n=94) carrying either the FV (n=178) or the FII variant (n=52) not suffering from additional thrombophilic risk factors were consecutively enrolled from 2 US centers and one German database. Antithrombotic therapy was performed according to standard protocols either with LMWH/vitamin K-antagonists (DVT) or LMWH/ASS (AIS) for 6 months (range: 3–indefinitive). Patients were followed for a median of 5.4 years (range: 1–23). FV children with first disease onset were significantly younger compared with patients in the FII group (p=0.02), and showed more abdominal vein thrombosis than children with the FII variant (p=0.02).

Following withdrawal of antithrombotic therapy a first recurrent event was diagnosed in 12 of 178 children with the FV mutation (6.7%), whereas pediatric patients with the FII mutation showed recurrent thrombosis in 6 of 52 patients (11.5%). Median (range) relapse time was 6.5 years (0.1–15.2) in FV carriers compared with 15 years (13–16) in the FII group (p=0.06). Interestingly, recurrent thrombotic events were recorded significantly more often in children with DVT compared with AIS (p< 0.001).

In conclusion, the clinical phenotypes of FVC and FII are different with respect to first thrombotic onset, and thrombotic locations, and recurrent thrombosis in both phenotypes occurred more often in DVT compared with AIS.