A sensitive immunoblotting technique to identify thyroxin-binding globulin protein heterogeneity after isoelectric focusing.

An enzyme-linked immunoblotting technique is described to detect thyroxin-binding globulin (TBG) variation in human plasma samples after isoelectric focusing in thin-layer polyacrylamide gels followed by transfer to a nitrocellulose membrane. The technique is used to demonstrate the polymorphic variation in thyroxin-binding globulin present in populations of African and Mongoloid origin and has enabled the detection of a new TBG variant in Eskimos. This technique eliminates the use of radioactive material and related expensive equipment. The technique is specific, sensitive, and reliable for the routine detection of genetic and epigenetic variation in thyroxin-binding globulin.