Several genetic variants of transferrin can be separated by polyacrylamide gel isoelectric focusing. Studies by other workers have revealed that the genetic type Tf C2 has an increased frequency in certain malfunctions which are associated with the formation of free radicals, suggesting that the iron binding of Tf C2 promotes the formation of hydroxyl radicals. In our study population of 20 patients with Alzheimer's disease, 13 had the C2 genetic subtype. Since the frequency of C2 in the South African population is 0.136 (14%), this represents a significant increase (p < 0.005) in the appearance of this genetic subtype.