Classification of transferrin (Tf) subtypes by isoelectric focusing.

A sample of 450 sera from unrelated individuals from Southern Germany was examined by isoelectric focusing on polyacrylamide gels. Three common subtypes, TfC1, C2-1, and C2, were differentiated. In addition, the rare variants TfB1, B1-2, B2, D1, D1-2, D2, and D3 were observed. The frequencies of the Tf alleles in our sample were found to be: TfC1 = 0.8544, TfC2 = 0.1367, TfB1 = 0.0011, TfB1-2 = 0.0022, TfB2 = 0.0045, and TfD1 = 0.0011. Analysis of 73 parents with 73 children did not show deviations from the expected mode of inheritance. Modification of the method by addition of 0.01 M FeCl3 to the sera prior to examination did, however, reveal further variation and permitted the distinction of six subtypes, C1, C2-1, C2, C3, C3-1, and C3-2.