Cation-exchange HPLC evaluated for presumptive identification of hemoglobin variants

Abstract

Abstract A battery of relatively simple tests allows the presumptive identification of hemoglobin (Hb) variants, making unnecessary structural analysis by protein chemistry methods or DNA sequencing. The primary step in this strategy involves the use of a matrix of electrophoretic mobilities obtained under various experimental conditions. This leads to an unambiguous result in ∼90% of the cases. Additional tests are required to characterize with more confidence the remaining 10%. We describe here the use of cation-exchange HPLC on the Bio-Rad Variant automated analyzer with the “β Thalassemia Short” program. By comparing the elution time of 125 human Hb mutants, we found that some variants with almost identical pI values or produced by the same type of amino acid substitution displayed different elution times. We present several examples in which use of the HPLC profile helped establish the diagnosis.