Screening of HbE by the New Screening Test: Alcohol HbE Test (AET)

Abstract

BACKGROUND: Hemoglobin E (HbE) is common in Thailand and the Indochina subcontinent. Implementation of a simple assay to screen for HbE is crucial for use in reproductive counseling, as HbE/β-thalassemia is a condition with high morbidity and mortality. METHODS: This report developed the alcohol-based HbE screening test named the Alcohol HbE Test (AET). This test was composed of 19% isopropanol in 0.005% Triton-X-100 aliquoted as a 500-µL volume in a 1.5 mL transparent microcentrifuge tube. In performing the AET, 50 µL of EDTA blood was added into the tube, incubated at 37 °C for 30 min before watching for precipitation by eye, which was seen for HbE carriers, not in normal. The test was validated, and assessed for the effect of hematocrit, stability of blood samples, stability of the AET reagent, and interference of HbH. RESULTS: The AET was effective, simple, and less costly than the conventional dichlorophenol indophenol precipitation (DCIP) test. Hematocrit had no effect on the AET results. EDTA blood samples kept in cold conditions (4 °C) were stable for at least 30 days, but only for 2 days at room temperature (30 °C). The aliquoted AET reagent was stable for 30 days in both conditions, while the unaliquoted AET reagent was stable for 6 months. Finally, HbH showed false positive results for the AET. CONCLUSIONS: The AET was successfully developed, and can be an alternative screening test for HbE carriers.