Alpha-antitrypsin Pi types in postmortem blood.

It is possible to determine alpha1-antitrypsin Pi types from serum obtained at necropsy. The Pi types were identical in 37 paired antemortem and postmortem samples. Blood transfusion in the 72 hours preceeding death may produce serum that cannot be typed. The frequency of the Pis allele was high in this study (0.074) and may reflect terminal alterations in alpha1-antitrypsin mobility and thus Pi typing, or a higher frequency in the population studied. The Pis allele was particularly frequent among Canadians with French names and Canadians born in Italy, Greece, and Portugal. The prevalence and severity of emphysema were not increased in PiA and Pis heterozygotes, but the groups studied were small and the variable, smoking, could not be adequately controlled. Studies of larger groups are recommended.