A further genetically determined transferrin variant in man

Summary Two families are described in which a new transferrin variant D4 is segregating. It has a mobility in starch gel electrophoresis at pH 8‐6 lower than that of transferrin C and higher than that of transferrin Dv The fact that it is different from D0 could be demonstrated using borate buffer, but not with the Tris/borate system. The familial distribution of the phenotype Tf CD4 suggests that individuals of this phenotype are heterozygous for genes, one of which is necessary for the formation of transferrin C and the other for transferrin D4. There is no suggestion that transferrin D4 is associated with any clinical abnormality, or with any other variation in serum protein formation. The frequency of the Tf CD4 phenotype is approximately 1 in 625.