Unexpected Detection of HbH-CS in a Pregnant Woman by Assessing HbA1c Using Capillary Electrophoresis

Testing for hemoglobin A1C (HbA1C) is useful for following up on glycemic control in diabetic patients as well as in pregnant women.A pregnant Chinese woman appeared for regular pregnancy check-ups. While monitoring blood glucose, an HbA1c test was initially performed in the pregnant Chinese woman using a CE-HPLC assay and capillary electrophoresis. Then acid gel Hb electrophoresis, a reverse dot-blot (RDB) assay, gap-PCR and DNA sequencing were applied to further evaluate the Hb variants.The CE-HPLC system has shown that the percentage of blood HbA1c was 5.4%, while hemoglobin electrophoresis of HbA2 and HbA0 were 1.6% and 88.7%, respectively. The capillary electrophoresis measurement results were 6.4% HbA1c, 0.4% HbA2, and 84.1% HbA0. HbA2 and HbA were 0.8% and 89.3%, respectively. Further gap-PCR, the reverse dot-blot (RDB) assay, and DNA sequencing showed that the pregnant woman had HbH-CS (αα CS/--) (1800 bp and 1300 bp) and β/β.Our study demonstrates that hemoglobin variants, such as HbH-CS can affect capillary electrophoresis results. An HbH-CS diagnosis in a pregnant woman is clinically significant. Laboratories should be cautious in using the CE-HPLC assay to evaluate HbA1c results in the presence of hemoglobin variants. Our findings highlight the strong discriminatory power of capillary electrophoresis for various Hb variants.