Protein C deficiency(PCD) is one of several hereditary abnormalities of inhibitor proteins that have been described in patients with a propensity for thromboembolic
complications. Mutations causing PCD has mainly identified Western countries and in the present study, we report a case of herediatry PCD with a missense
mutation(C6218T) in a year old male with multiple cerebral infarction and transient ischemic attack. The protein C actively (46%) and antigen(51%) levels were decreased to be consistent with hyterozygous type 1 PCD. To our knowledge, this is the second Korean case of hereditary PCD with the same genetic (C6218T), which may be hot sports for mutation in the protein C gene.