Electrophoretic variability in human head hair: Polyacrylamide gel electrophoresis of hair proteins in the presence of sodium dodecyl sulfate and urea

A fast and simple procedure for routine typing of human head hair is described. Hair proteins, extracted in a solution containing sodium dodecyl sulfate, urea and dithiothreitol were separated electrophoretically in the presence of 6 M urea. On examination of hair from 445 different individuals, eight characteristic polypeptide patterns (phenotypes) could be distinguished and were arbitrarily named K1 to K8. Three of them, K1, K2 and K3 occur frequently, especially K1, which is found in approximately 79% of the individuals investigated. The eight phenotypes are characterized by the different number and patterns of major polypeptide bands in the range of 45 to 60 kDa. Based on the high reproducibility it can be assumed that a given phenotype is specific for the head hair of an individual. Electrophoretic keratin typing is a promising tool for hair analysis in genetic and forensic investigations.