Differences of frequency distributions of plasminogen phenotypes between Japanese and American populations: new methods for the detection of plasminogen variants.

Frequency distributions of various plasminogen phenotypes in Japanese and American white populations were studied using electrofocusing in polyacrylamide gels followed by zymography and immunofixation. Using a synthetic substrate, tosyl-lysine-alpha-naphthyl ester, for zymography allowed zymography and immunofixation to be performed sequentially on the same gel plate. By this method, a nonfunctional abnormal plasminogen variant, plasminogen Tochigi, was readily detected in both plasma and serum. The gene frequency of this abnormal variant in a Japanese population was 0.018, whereas the abnormal variant was not detected in an American white population, suggesting the very rare occurrence of this variant in whites. Two common alleles, A and B, clearly identified in neuraminidase-treated samples, were observed at gene frequencies of 0.98 and 0.003, respectively, in the Japanese. These values are significantly different from the reported values in whites of 0.69 for A and 0.3 for B.