Prenatal diagnosis of hemoglobin Bart's hydrops fetalis by HPLC analysis of hemoglobin in fetal blood samples.

Since HbF and HbA are not found in fetuses with Hb Bart's hydrops fetalis the feasibility of prenatal diagnosis of homozygous alpha-thalassemia 1 by fetal hemoglobin typing was examined. Blood samples were obtained from fetuses at 18 to 22 weeks of gestation by cordocentesis in 32 pregnant women at risk of having a child with homozygous alpha-thalassemia 1 (alpha-thal-1). The samples were analyzed by a PCR-based method for the diagnosis of alpha-thal-1 (SEA type) and the proportion of hemoglobin fractions were determined by automated HPLC. DNA analysis showed that 8 of the 32 fetuses were homozygotes for alpha-thal-1, 17 were heterozygous for alpha-thal-1 (alpha-thal-1 trait), and a normal complement of four a-globin genes was found in 7 cases. The Hb typing in fetuses with homozygous alpha-thal-1 showed a peak of unbound Hb (Hb Bart's and Hb Portland) and no HbF, HbA and HbA The alpha-thal-1 trait chromatograms showed unbound Hb, pre HbF, HbF and HbA peaks. The chromatogram of normal fetuses showed HbF and HbA peaks without HbA2. In these cases the HbA proportion is between 3% and 10% with no apparent differences between the 18h and 22nd week of gestation. As the analysis of fetal Hb types by HPLC is facile and speedy and the results correspond with those obtained by DNA analysis, fetal Hb typing by automated HPLC is a convenient prenatal diagnostic method for homozygous alpha-thal-1. The method is recommended for prenatal diagnosis in populations with a high frequency of alpha-thal-1.

Frequency of alpha-thalassemia-1 of the Southeast Asian-type among pregnant women in northern Thailand determined by PCR technique.

Five hundred pregnant women were analyzed for the presence of alpha-thalassemia-1 of the Southeast Asian (SEA)-type by polymerase chain reaction (PCR) technique at the Maharaj Nakhon Chiang Mai University Hospital in Chiang Mai during the period from April to June 1995. Forty-four of them (8.8%) were recognized as carriers, corresponding to a frequency of 0.044. Homozygous alpha-thalassemia-1 of the SEA-type, the fatal condition of hemoglobin Bart's hydrops fetalis, has an expected frequency of 0.00194, or about 2 hydrops fetalis cases per 1,000 births in this population.

Malnutrition and growth abnormalities in children with beta thalassemia major.

Abnormal linear growth (stunting) is characteristic of children with beta thalassemia major and has been variably and inconsistently attributed to multiple different mechanisms. Despite the coexistence of beta thalassemia with deficits of several micronutrients, global undernutrition as a principle cause of growth abnormalities has not been adequately studied. We prospectively studied 115 nonsplenectomized children (6 months-6 years, 54 males, 61 girls) with beta thalassemia major who has not previously received chelation therapy. Most children had abnormal weight-for-age (WAZ) and height-for-age (HAZ) Z scores, however female children had lower WAZ (p < 0.0001) and HAZ (p < 0.02) compared to males. Mild to moderate degrees of acute wasting was also usual, and two males and one female had severe wasting. Severe weight deficits were more prevalent in the youngest (p < 0.01) and severe stunting in the older (p = 0.01) children. Nearly all children were < 50th percentile for both weight-for-age and height-for-age, and the majority were < 5th percentile. Of note, children were also disproportionately distributed below the 50th percentile for weight-for-height. Pre-transfusion hemoglobin was variably associated with anthropometric measurements. We conclude that not only is linear growth failure pervasive in our population with beta thalassemia major, but varying degrees of wasting are also typical. Further, weight deficits occur at an early age and appear to precede deficits in linear growth. Abnormal growth is not due to chelation therapy and is inconsistently associated with the degree of anemia. These patterns of growth abnormalities indicate general malnutrition as an important cause of growth failure in children with beta thalassemia.

Determination of hemoglobin Bart's in alpha thalassemia traits by two-site immunoradiometric assay. II. Detection of hemoglobin Bart's in alpha thalassemia traits.

A sensitive method for the determination of minute amounts of Hb Bart's in hemolysate of alpha thalassemia-1 and alpha thalassemia-2 was carried out by two-site immunoradiometric assay. This technique is very sensitive and is able to detect minute amounts of substances. When this method is used with specific anti-Hb Bart's derived from affinity column chromatography, then labelled with radioactive 125I, the two-site immunoradiometric assay will contain both the sensitivity and specificity for the determination of Hb Bart's. In this study, parents of fetus with Hb Bart's hydrops fetalis contained high levels of Hb Bart's 0.73-1.11 per cent (mean +/- S.D. = 0.86 +/- 0.12%). Parents of Hb H diseases had Hb Bart's in two groups. The first group contained high levels of Hb Bart's of 0.73-1.20 per cent (mean +/- S.D. = 0.88 +/- 0.14%), while the second group had levels of 0.39-0.45 per cent (mean +/- S.D. = 0.42 +/- 0.02%). Mothers of patients with Hb H disease contained Hb Bart's of 0.42 +/- 0.48 per cent (mean +/- S.D. = 0.45 +/- 0.02%). Eight out of ten normal subjects contained low levels of Hb Bart's of 0.17-0.26 per cent (mean +/- S.D. = 0.22 +/- 0.04%), while two contained high levels of Hb Bart's of 0.46 and 0.43 per cent respectively. The two-site immunoradiometric assay was able to differentiate the level of Hb Bart's among alpha thalassemia-1, alpha thalassemia-2 and normal subjects.

Determination of hemoglobin Bart's in alpha thalassemia traits by two-site immunoradiometric assay. I. Purification of hemoglobin Bart's and preparation of specific anti-Hb Bart's.

This research report describes methods for the preparation of hemolysate and the isolation and purification of hemoglobins Bart's, A, A2, E, F and H. Procedures for the preparation of anti-Hb Bart's by injecting purified Hb Bart's into rabbits is indicated in the time schedule. The rabbit antisera were evaluated by antigen-antibody reaction in agar gel. Although the antiserum reacted with Hb Bart's but not with Hb A, A2,E and H, it also cross-reacted with Hb F. After the rabbit antisera were absorbed with Hb F, the antisera were highly specific because it only reacted with Hb Bart's. The purified specific anti-Hb Bart's was labelled with radioactive 125I by chloramine-T method. After passing through Sephadex G-100 column, the 125I labelled specific anti-Hb Bart's was obtained in the first peak. This radioactive labelled anti-Hb Bart's was ready to use in the two-site immunoradiometric assay.