Plasminogen with type-I mutation is polymorphic in the Japanese population.

A functionally inactive plasminogen (PLG) variant designated as PLG M5 is polymorphic in the Japanese population and has a feature common to PLG with type-I mutation that has a codon 601 missense mutation in exon 15 (GCT for Ala-->ACT for Thr). This study was conducted to clarify whether the type-I mutation of PLG is present in PLG M5 and polymorphic in the Japanese population. Direct sequencing of the amplified DNA from the PLG gene in a heterozygote for PLG M5 revealed that the sequence of the exon 15 in the gene for PLG M5 is identical with that in the PLG gene with type-I mutation. In addition, the amplified DNA from the PLG gene in 12 heterozygotes for PLG M5 reacted with the probe for the type-I mutation in dot blot hybridization with an allele-specific oligonucleotide probe. The heterozygote for PLG with type-I mutation was found in 2.2% of 360 unrelated healthy subjects. These data indicate that the type-I mutation of PLG is present in PLG M5 and polymorphic in the Japanese population. The data also suggest that the PLG M5 is identical with PLG Tochigi and Kagoshima.