The prothrombin gene G20210A variant in an unselected thromboembolic population. A Belgian prospective clinical study

The presence of the 2021 OA allele of the prothrombin
gene has recently been shown to be a risk factor of venous
thromboembolism, probably mediated through increased
prothrombin levels. The aim of the study was to determine
the frequency of the prothrombin 2021 OA allele in 193
consecutive unselected patients with venous thromboembolism
and 100 healthy controls and to analyze the clinical
profile associa!ed wi~h this new inherited thrombophilic
factof. In agreement with previous reports, we found a
frequency of 7.3% of heterozygous carriers of the 2021 OA
allele among patients and 1% among controls. We confirm
that plasma prothrombin levels are more elevated in
the individuals bearing the prothrombin 20210A allele
compared with those who do not. We did not find any relationship
between the presence of the prothrombin
2021 OA allele and either a family history of thromboembolism,
the rate of recurrences or the age at disease onset.
However, the co-inheritance in the same individual of both
prothrombin 2021 OA allele and factor V Leiden was associated
with a significantly lower age at disease onset suggesting
a synergistic contribution of both abnormalities.