A case of venous thromboembolism caused by protein C deficiency due to a novel gene mutation.

Hereditary protein C (PC) deficiency is a quantitative or qualitative abnormality of the coagulation regulator PC resulting in a decreased PC activity. It is caused by mutations in the PC gene (PROC) located on chromosome 2q13-q14. Although hereditary PC deficiency is an important risk factor for venous thromboembolism (VTE), it is often overlooked because of difficulties in genetic examination. The low prevalence of this disease has led to a lack of evidence for its treatment. We report the case of a 21-year-old male with VTE caused by hereditary PC deficiency due to a novel PROC gene mutation, c.566G>A, p.Arg 189 Gln. The patient was refractory to treatment with direct oral anticoagulants, but responded to catheter-directed thrombolysis. Further intrafamilial genetic survey revealed the presence of the same mutation in five of the six family members. Learning objectives: Venous thromboembolism (VTE) caused by hereditary protein C deficiency that is refractory to direct oral anticoagulants may respond to catheter-directed thrombolysis. Furthermore, the first VTE in young patients with a strong family history and female family members of childbearing age should be considered for genetic testing. In addition, genetic examination will help establish evidence for the treatment of such patients.