Materials and Methods

from two diabetic patients, analyzed for Hb A10by HPLC, were found to contain additional Hb peaks. The presence of an abnormal Hb was confirmed in both instances by hemoglobinopathy studies. Structural studies determined the two Hb variants to be Hb Manitoba (a2 102 Ser-Arg,J and Hb G-Coushatta (afi2 22 Glu-.Ala). The signifi-cance of the presence of an abnormal Hb in Hb A10 analysis is discussed. AddItional Keyphrases: chromatography, reversed-phase-hemoglobin variants Since the 1960s, ithas been known that hemoglobin (Hb) fractions in erythrocytes are heterogeneous and contain various minor amounts of modified Hb (1). The minor glycohemoglobin form, Jib A1, is a glycated form of Hb A and is found in increased amounts in diabetic patients (2,3). Jib A10has become very important in the monitoring of long-term control of diabetic patients, and numerous laboratory procedures, including micro-col-umn chromatography, immunoassay, and electrophore-sin,have been developed for its measurement (4-6). For quantification of several specimens, many clinical labo-ratories use either the commercially available affinity columns (7) or HPLC programs for analyzing Hb A10 (8). The latter procedure underestimates the quantity of Jib A10 in the presence of abnormal Hb because the minor fractions of these Hb variants, which can be glycated as well, will not be included in the total glycated fraction (9, 10). Here we describe two such variants