Common risk factors for CTEPH include unexplained, recurrent, or large clotted PEs, elder age, a chronic inflammatory state, and malignancy.[2] CTEPH pathology may also be associated with high aPL titers,[9] as several cohort studies report aPL-positive titers in ∼15% to 50% of CTEPH patients.[10,11] aPLs may induce CTEPH by inhibiting cascade reactions catalyzed by phospholipids or by promoting microembolization.[12] Indeed, high titers of lupus anticoagulant are associated with microembolization in PAPS, where higher aPL titers correlate with a worse prognosis.[13]. Here, FASLG is linked to chronic thromboembolic pulmonary hypertension.