Human orosomucoid (ORM1) subtyping: further population genetic data and reports on the feasibility to type aged blood samples and stains.

Genetic polymorphism of serum orosomucoid (ORM1) was investigated in 1072 unrelated German Caucasians using isoelectric focusing followed by Western blotting and EIA. The estimated allele frequencies were ORM1 *F1 = 0.5690, ORM1 *S = 0.3927, ORM1 *F2 = 0.0368, ORM1 *F2S = 0.0009 and ORM1 *F5 = 0.0005. The method was successfully applied to determine ORM1 phenotypes in aged blood samples and blood stains. The results indicated that the ORM protein is a informative and remarkably robust blood group system.