Protein S deficiency is common in a healthy Thai population

Currently, venous thromboembolism is a growing menace in Asians, approaching to that of Western countries. The most common genetic mutations causing thrombosis in Caucasians are factor V Leiden and prothrombin mutation. However both are very rare in Asians. On the other hand, natural anticoagulant protein (protein S, protein C and antithrombin) deficiencies are more common in Asian than in Western thrombotic patients. The prevalence of these deficiencies is very low in healthy Caucasians (0.02-0.3%). It is possible that the prevalence is higher in an Asian general population. However there have been very few prevalence studies to prove this hypothesis. Protein S deficiency was found in 3.7% (13/352, 95% confident interval 1.72-5.66) healthy Thais. Seven of them were type III deficiency. Similar to previous studies, total and free protein S levels were lower in females, but positively and negatively correlated with age, respectively. In contrast, one protein C deficiency (0.27%, 1/370) and no antithrombin deficiency (0/206) were detectable in our population. Furthermore, the authors found that antithrombin was significantly lower in women and there was a positive correlation between protein C activity and age. In conclusion, protein S deficiency is more common in Thais than in Caucasians. This result remains to be confirmed by a large population-based study.