Literature reports this variant as a risk factor for venous thrombosis and ischemic stroke, primarily in East Asians, not strictly following Mendelian inheritance.22, 23This in-frame deletion of three bp is expected to shorten the encoded protein in the C-terminal region of the light chain which harbors a crucial functional motif essential for its interaction with protein S, as well as factors Va and VIIIa.24Based on clinical presentations and coagulation indicators of family members, the primary pathogenic variant is c.661T > C, as all carriers exhibit thrombosis. The gene discussed is PROS1; the disease is deep vein thrombosis.