Interference of hemoglobin Hope on beta-thalassemia diagnosis by the capillary electrophoresis Method

Fluorescence spectroscopy as a novel technique for premarital screening of sickle cell disorders

Spectral diagnostic screening for sickle cell disease was carried out on volunteer blood samples (N = 100). The samples were subjected to different diagnostic methods including conventional complete blood count (CBC), hemoglobin electrophoresis (HBE) and spectral diagnosis. For the spectral diagnostic method, we discriminated three different characteristic spectral features. In total, 15 samples were sickle cell trait (SCT), 34 samples were sickle cell disease (SCD), and the rest of the samples (N = 51) were normal controls. The spectral discrimination of the three different sets of samples was distinguished on the quantification of fluorescent biomolecules such as tyrosine, tryptophan, NADH, FAD, and porphyrins. The results were compared with the conventional standard CBC and capillary electrophoresis findings. The spectral diagnosis method exhibited a sensitivity and specificity greater than 90 % for the tested samples. This technique requires only 5 mL blood samples, has an analysis time of 20 min, exhibits high accuracy and may be used in small clinics in remote villages.

The shortcut strategy for beta thalassemia prevention

We propose antenatal blood tests using high-resolution DNA melting (HRM) analysis for beta thalassemia mutation detection after hemoglobin A₂ estimation as a modified strategy for the identification of beta thalassemia at-risk couples. Antenatal blood samples of 1,115 couples were transferred from the antenatal care clinic. Hemoglobin A₂ was quantified, and proportions ≥3.5% were further assessed for beta thalassemia mutation using HRM analysis. Twelve types of beta thalassemia mutations, including hemoglobin E, were identified. There were 23 couples who were detected as at-risk. All at-risk couples were identified within 7 working days after sample receipt. Prenatal diagnosis revealed 6 affected fetuses. One fetus was homozygous CD17 (AT), and five fetuses exhibited beta⁰ – thalassemia/hemoglobin E disease. These results were consistent with the outcomes calculated using the Hardy-Weinberg equation. Antenatal blood tests for mutation detection using high-resolution DNA melting analysis after hemoglobin A₂ estimation is a feasible laboratory method for the recruitment of couples with a fetus that is at risk for beta thalassemia. This modified strategy is cost-effective and may be beneficial for use in a beta thalassemia prevention program.

Detection of Co-inheritance of Hb Hope and Hb Constant Spring in Three Thai Samples by Capillary Electrophoresis

The diagnosis of co-inheritance of Hb Hope [β136(H14)Gly → Asp, GGT > GAT] and Hb constant spring [Hb CS; α142, Term → Gln (TAA > CAA IN α2)] by high performance liquid chromatography (HPLC) is difficult because Hb Hope has a HPLC elution pattern similar to that of Hb Pyrgos, Hb New York, Hb Kodaira, and Hb Phimai. Moreover, the Hb CS mRNA, as well as the gene product, are unstable and present at a low level in peripheral blood. We report the use of a capillary electrophoresis (CE) for diagnosis of co-inheritance of Hb Hope and Hb CS in 3 Thai females who had mild anemia with Hb and Hct varying from 91-114 g/L to 0.28-0.36 L/L, respectively. Hb Hope eluted with a retention time of 125-140 s (Zone 10) of CE electrophoregram. Furthermore, the peak of Hb CS at the retention time of 245-250 s (Zone 2) was observed in these samples. In addition, the manual analysis by taking the non-black area under both peaks of HbA and Hb Hope (inverted V) into account provided the corrected Hb CS levels which are useful in screening of heterozygote or homozygote for Hb CS. Thus, the CE method provides an accurate diagnosis of Hb Hope and Hb CS which is useful in genetic counseling, prevention and control programs for these hemoglobinopathies.

Interference of the Hope Hemoglobin With Hemoglobin A1c Results

Hemoglobin A1c (HbA1c) is now considered to be the marker of choice in diagnosis and management of diabetes mellitus, based on the results of certain landmark clinical trials. Herein, we report the case of a 52-year-old ethnic Southeast Asian Indian man with impaired glucose tolerance whose glycated hemoglobin (ie, HbA1c) levels, as measured via Bio-Rad D10 high-performance liquid chromatography (HPLC) and Roche Tina-quant immunoassay were 47.8% and 44.0%, respectively. No variant hemoglobin (Hb) peak was observed via the D10 chromatogram. We assayed the patient specimen on the Sebia MINICAP capillary electrophoresis platform; the HbA1c level was 6.8%, with a large variant Hb peak of 42.0%. This finding suggested the possible presence of the heterozygous Hb Hope, which can result in spuriously elevated HbA1c results on HPLC and turbidimetric immunoassays. Although the capillary electrophoresis system was able to identify the variant, the A1c results should not be considered accurate due to overlapping of the variant and adult Hb peaks on the electrophoretogram reading. Hb Hope is usually clinically silent but can present such analytical challenges. Through this case study, we critically discuss the limitations of various HbA1c assay methods, highlighting the fact that laboratory professionals need to be aware of occurrences of Hb Hope, to help ensure patient safety.

Coinheritance of Hb S [β6(A3)Glu→Val, GAG>GTG] with β0-thalassemia codon 17 (A>T) in a Thai patient

Hb S [β6(A3)Glu→Val, GAG>GTG] is a β-globin gene variant that has a very low incidence in the Thai population. Coinheritance of Hb S and β(0)-thalassemia (β-thal) can result in severe clinical conditions. This study reports the case of a Thai patient with a compound heterozygosity for Hb S and β(0)-thal codon 17 (A>T). His hemoglobin (Hb), hematocrit (packed cell volume, PCV), mean corpuscular volume (MCV) and mean corpuscular Hb (MCH) levels were all less than the lower limits, while red cell distribution width (RDW) was higher than the upper limit. Levels of Hbs S, F and A(2) detected by high performance liquid chromatography (HPLC) were comparable to those from capillary electrophoresis (CE). As Hb S has a similar electrophoretic mobility and the HPLC profile is also similar to those of Hb Tak [β147, Term→Thr (+AC)] and Hb D-Punjab [β121(GH4)Glu→Gln, GAA>CAA], DNA sequencing was then performed. This was to detect β(0)-thal, and to differentiate Hb S from the Hb Tak and Hb D-Punjab mutations. The β(0)-thal codon 17 and Hb S mutations were detected indicating that coinheritance of these two mutations can be found in the Thai population. Therefore, to provide proper clinical management and genetic counseling of this rare case, DNA analysis should be performed in all cases when a peak at the S-window is detected by HPLC or CE.