Polymorphism of complement factor I: population study in Japanese and phenotyping in bloodstains

Abstract

Polymorphism of the complement component factor I (IF) was investigated in 645 unrelated Japanese individuals using isoelectric focusing and immunoblotting. The allele frequencies were IF*A = 0.1031 and IF*B = 0.8969. The population data fitted the Hardy-Weinberg law. Phenotyping was also possible from bloodstains stored at 37 degrees C for up to 1 week, at room temperature for up to 2 weeks and at 4 degrees C for up to 5 weeks. The IF system can be a useful supplement for the medicolegal identification of bloodstains, but seems useless in Caucasoids.