Hb Belleville [β10(A7)Ala→Thr] Affects The Determination of Hb A1c by Routine Cation Exchange High Performance Liquid Chromatography

Abstract

When analyzed by routine cation exchange high performance liquid chromatography (HPLC), the Hb A1c peak of a Caucasian diabetic patient from Yorkshire, UK, appeared to be an incompletely resolved doublet. One component (5.5%) eluted at the normal time for Hb A1c, whereas the other component (6.6%) eluted slightly later. The HPLC trace was otherwise normal. Analysis of the diabetic patient's blood and a tryptic digest thereof by electrospray ionization mass spectrometry (ESI-MS) identified the Hb Belleville trait. To relate Hb A1c determined by HPLC to α and β chain glycation determined by ESI-MS, several normal blood samples (5–14% Hb A1c) were analyzed by both techniques. The Hb A1c levels derived from the α and β chain glycation levels of the diabetic patient (12.9 and 12.4%, respectively) agreed with the sum of the two peaks (12.1%) in the HPLC trace. Similarly, Hb Belleville was detected and identified in another Caucasian, also from Yorkshire, with normal Hb A1c.