Primary Thrombophilia in México XI: Activated Protein C Resistance Phenotypes are Multifactorial.

Activated protein C resistance (aPCR) phenotypes represent around 20% of the laboratory findings in Mexican Mestizos having suffered thrombosis and displaying clinical markers of thrombophilia. In a single institution for a 276-month period, 96 Mexican mestizos with a history of thrombosis and clinical markers of a primary thrombophilic state were prospectively studied to identify a thrombophilic condition. An abnormal aPCR phenotype was identified in 18 individuals. Evaluation of those with an abnormal aPCR phenotype, identified that 44% had factor V Leiden mutation, 22% increased levels of factor VIII, 16% anti-phospholipid antibodies and 6% a lupus anticoagulant. In the remaining 22%, the use of direct oral anticoagulants (DOACs) in the past period of 12-24 h was recorded. We found significant associations between abnormal aPCR phenotype and the factor V Leiden mutation (p = 0022), between abnormal aPCR phenotype and the use of DOACs (p = 0.006) and between antiphospholipid antibodies and lupus anticoagulant (p < 0.0001). These data are consonant with those observed in other populations and further identify that consideration be given to identifying whether individuals are being treated with the novel DOACs when conducting laboratory studies oriented to identify the etiology of thrombosis.