Evaluation of automated glycohemoglobin analyzer HLC-723G7 beta-thalassemia analysis mode

We evaluated the new automated glycohemoglobin analyzer HLC-723G7 (G7) intended for beta-thalassemia diagnosis to determine correlation of hemoglobin (Hb) F and Hb A2 quantitation with the Variant beta-Thalassemia Short Program and to evaluate the performance of the G7 analyzer. Two hundred fifty EDTA blood samples with Hb A, A2, and F by Variant were analyzed for Hb A2 and Hb F by G7 device. Recovery, precision, and interference of the G7 analyzer were studied. The R2 values for Hb A2 and Hb F were 0.963 and 0.640, respectively. Recovery of Hb A2 and Hb F of low and high control samples ranged from 96% to 100% and 91% to 101%, respectively. The coefficients of variation (CVs) of intraassay precision ranged from 1.3% to 3.9% for Hb F and 0.0 to 1.9% for Hb A2. The CVs of interassay precision ranged from 1.9% to 5.6% for Hb F and 2.5% to 3.0% for Hb A2. The CVs for Hb F in both conjugated bilirubin and chyle substance groups were higher than the CVs for Hb A2. This evaluation revealed very good correlation of Hb A2 measurement between the G7 and the Variant devices. The performance evaluation demonstrated good recovery, precision, and low interference of both Hb A2 and Hb F measurements.

Usefulness of automated chromatography for rapid fetal blood analysis for second trimester prenatal diagnosis of beta-thalassemia

Prenatal diagnosis of beta-thalassemia is now ideally done in the first trimester of pregnancy by chorionic villus tissue DNA analysis. Nevertheless, fetal blood analysis in the second trimester is required either when the mutation in both parents cannot be characterised or when the couple comes late for investigations. We evaluated the usefulness of analysis of fetal blood on the Biorad Variant Hemoglobin Testing System using the beta-thalassemia short programme in comparison with the conventional globin biosynthesis in 58 pregnancies. The beta/alpha biosynthesis ratios in 13 homozygous fetuses ranged from 0 to 0.03 and the adult hemoglobin (HbA) levels by automated chromatography varied from 0% to 0.4%. The normal or heterozygous fetuses had beta/alpha ratios of >0.04 and HbA levels ranging from 2.1% to 10.6%. In 17 fetuses we also correlated the beta gene mutations with the predicted genotypes using automated high-performance liquid chromatography (HPLC). Follow-up of 18 unaffected fetuses using the Variant System at birth showed a significant increase in HbA levels.

Prenatal diagnosis of beta-thalassemia major by high-performance liquid chromatography analysis of hemoglobins in fetal blood samples

In Thailand and adjacent countries, most of the beta-thalassemia genes are beta(0)-thalassemia mutations that prevent the production of Hb A. We propose the quantitation of the Hb A fraction in fetal blood in the mid-trimester of pregnancy by automated high performance liquid chromatography as a reasonable prenatal diagnostic method to be applied in areas with limited laboratory facilities. Forty pregnant women at risk of delivering a child with beta-thalassemia major were identified using an erythrocyte osmotic fragility test and quantitation of Hb A2. Cordocentesis was performed at the gestational age of 18-22 weeks and fetal blood was analyzed for hemoglobin fractions by automated high performance liquid chromatography. The beta-globin gene mutations were characterized by beta-globin gene sequencing. The 4 bp deletion at codons 41/42 (-TTCT) was the most frequent of the 40 beta-thalassemia mutations observed (20/40 = 50%), followed by the splice site mutation IVS-I-1 (G-->T) (7/40 = 17.5%), the nonsense mutation at codon 17 (A-->T) (7/40 = 17.5%), the nonsense mutation at codon 35 (C-->A) (3/40 = 7.5%), and the beta(+)-thalassemia promoter mutation at -28 (A-->G) (3/40 = 7.5%). High performance liquid chromatography revealed nine fetuses which had only Hb F and no Hb A. All were homozygotes or compound heterozygotes for beta(0)-thalassemia mutations. In the remaining 31 fetuses, a Hb A peak was present in the chromatograms. One fetus with 0.5% Hb A was a compound heterozygote for the -28 (A-->G) and codons 41/42 (-TTCT) mutations. In the remaining 30 fetuses, the Hb A values ranged between 0.8 and 7.4%. Twenty of these, with a Hb A concentration of 1.82 +/- 0.49% (range 0.8-2.8%), were beta-thalassemia heterozygotes. The remaining 10 fetuses had Hb A values of 4.89 +/- 1.47% (range 2.9-7.4%) and normal beta-globin genes. The absence of Hb A in homozygotes or compound heterozygotes for beta(0)-thalassemia mutations and the presence of measurable amounts of Hb A in heterozygotes and normal homozygotes, permits the diagnosis of fetuses expected to develop postnatal beta-thalassemia major.

Rapid mid-trimester prenatal diagnosis of beta-thalassaemia and other haemoglobinopathies using a non-radioactive anion exchange HPLC technique--an Indian experience

Anion exchange high performance liquid chromatography (AX-HPLC) has been widely used for separating and quantifying various haemoglobin fractions especially in the haemoglobinopathies. We have evaluated the reliability of this technique to measure low concentrations of adult haemoglobin (HbA) in fetal blood to enable differentiation between affected and unaffected fetuses at risk for beta-thalassaemia (85) and other haemoglobinopathies such as delta beta/beta-thalassaemia (1), E-beta-thalassaemia (2), S-beta-thalassaemia (1), and sickle cell anaemia (1). The HbA values obtained ranged between 0 and 9.51 per cent. The HbA for 27 affected fetuses was 0 per cent, while two showed a HbA value of 0.5 per cent. The mean HbA for 61 unaffected fetuses was 4.8 +/- 2.08 per cent. Thirty cord blood samples (cord abortus in cases of affected fetuses and cord full term in cases of unaffected fetuses) were analysed to reconfirm the diagnosis. Ten babies between 8 and 18 months of age could be followed up for confirmation. AX-HPLC was found to be a simple and rapid procedure with high sensitivity and there was a good correlation between the HbA values obtained by AX-HPLC and the diagnosis by carboxymethyl cellulose (CMC) chromatography.