Plasma levels of factor XII activity (A) and antigen (B) of individuals with 46C/C, 46C/T, or 46T/T. Thirteen Caucasians were included in C/C, 6 in C/T, and 1 in T/T group. The levels of plasma FXII activity and antigen were 150.0±30.3 (n = 20) and 155.4±36.1 (n = 20) in Caucasians, and 125.4±56.3 (n = 31) and 104.7±57.2 (n=20) in Orientals, respectively.