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PubMedDate not supplied

Generation of transgenic mice expressing human hemoglobin E.

Hemoglobin E (HbE, beta26 Glu-->Lys) is the most common abnormal Hb variant in the world, and found in greatest frequency in Southeast (SE) Asia. In the United States, HbE is the third most prevalent variant (after HbS and HbC); and its now increasing frequency is due to immigration from SE Asia. HbE homozygotes present a benign clinical picture, but when HbE is coupled with beta0-thalassemia or HbS, variably severe hemoglobinopathies arise. To date, there are no transgenic animal models of HbE-related diseases. We report here the creation of transgenic mice expressing human HbE as a step toward creating animal models for HbE-related diseases. The betaE mice exhibit red blood cell hypochromia and target cells consistent with those observed in human patients exhibiting HbE trait. Furthermore, the transgenic HbE hemolysates contain increased amounts of Hb oxidation products.

Animals↗
PubMed1975

Maternal and fetal outcome associated with hemoglobin E trait and hemoglobin E disease.

A study of 20 patients with hemoglobin E trait abnormality and 8 patients with hemoglobin E disease in pregnancy is presented. The hematologic abnormality in HbE hemoglobinopathy is mild though hemoglobin values are significantly lower than in HbA patients. Fetal wastage is no increased and the salvage rate is high (live births over 95 per cent). The mean birthweight of the baby in HbE patients is significantly lower than in HbA patients, but the incidence of prematurity is not significantly increased in HbE patients. Blood loss at delivery is not markedly affected by hemoglobin type. The incidences of postpartum hemorrhage, preeclampsia, and malaria are not significantly increased in HbE patients; the reason for the significant increase in incidence of abruptio placentae in HbE is not known. No maternal deaths or congenital fetal abnormalities were recorded. It is concluded that the course of pregnancy in HbE trait abnormality and HbE disease is relatively benign.

Abortion, Spontaneous↗
PubMed1992

Differentiation of homozygous hemoglobin E from compound heterozygous hemoglobin E-beta O-thalassemia by hemoglobin E mutation analysis.

OBJECTIVES: To facilitate the differential diagnosis of hemoglobin FE in newborn infants (homozygous hemoglobin E vs hemoglobin E-beta O-thalassemia). METHODS: The beta-globin gene in DNA from infants found to have hemoglobin FE in the California newborn screening program was amplified by the polymerase chain reaction, and the product was digested with Mnl I, which fails to cut the product when the hemoglobin E mutation is present. When both amplified alleles fail to be cut, homozygous EE is diagnosed. If only one allele is cut, a beta-globin allele without the E mutation is present (non-E), which is most likely a gene with a beta O-thalassemia mutation. RESULTS: Samples from 18 infants revealed an EE genotype, and from two samples a non-E/E genotype was determined. Clinical examination of these two patients confirmed a diagnosis of hemoglobin E-beta O-thalassemia. An independent clinical diagnosis agreed with DNA analysis for all 17 of the 20 infants for whom follow-up and family studies were available. The DNA results were obtained within a week, but the clinical diagnoses often could not be resolved unequivocally for months. CONCLUSIONS: The direct analysis of patient DNA samples for the hemoglobin E mutation allowed rapid and accurate diagnosis in this sample of infants with hemoglobin FE on the newborn screen. This rapid discriminatory test should reduce cost and simplify the diagnostic approach for these patients, which currently consists of expensive and lengthy follow-up until clinical data and family studies result in a diagnosis.

Asian↗
PubMed2005

Hemoglobin E levels in double heterozygotes of hemoglobin E and SEA-type alpha-thalassemia.

Coinheritance of alpha-thalassemia and hemoglobin E (Hb E) is prevalent in Thailand, where the gene frequencies of thalassemia and hemoglobinopathies are high. Hb E carriers with, concomitant inheritance of alpha-thalassemia 1 are known to have a lower level of Hb E. In this study, we reviewed the Hb E levels in Hb E carriers, who either had or did not have Southeast Asian (SEA)-type alpha-thalassemia, in order to seek a Hb E level that may be used as a predictor for concomitant alpha-thalassemia carrier status. The Hb E levels as measured by microcolumn chromatography in 844 Hb E carriers detected during a prenatal screening program for severe thalassemia at Chiang Mai University Hospital were reviewed. Hb E levels ranged from 12.3-35.0% (23.3 +/- 3.1%) in 751 Hb E carriers without SEA-type alpha-thalassemia and from 11.6-32.0% (17.0 +/- 3.7%) in 93 concomitant Hb E and SEA-type alpha-thalassemia carriers. The difference was significant (p < 0.01). However, the absence of SEA-type alpha-thalassemia could not be predicted by the higher Hb E level alone, as 3% of double heterozygotes demonstrated a level of more than 25%. Our study confirms a lower Hb E level in double heterozygotes with Hb E and SEA-type alpha-thalassemia. Nevertheless, the difference does not provide sufficient discriminatory power for the reliable exclusion of alpha-thalassemia status.

Chromatography↗
PubMed2006

Development of severe anemia during fever episodes in patients with hemoglobin E trait and hemoglobin H disease combinations.

Globin chain imbalance and tissue hypoxia are important determinants of the clinical severity of thalassemias. Phenotypic expression may be further modified by interactions between alpha- and beta-thalassemia defects. We retrospectively and prospectively studied the clinical and hematologic features in children and adults with hemoglobin (Hb) E trait/Hb H disease (SEA/Paksé) (seven cases) and Hb E trait/Hb H disease (SEA/Constant Spring) (29 cases) and found that they had similar presentations. The severity of these two intermediate thalassemic manifestations ranged from very mild to severe. Severe anemia developed in accordance with very high fever, whereupon the range of Hb and hematocrit (Hct) levels declined to 5.2-5.8 g/dL and 13%-19%, respectively. In one case, during a hemoconcentrated state as occurs in dengue hemorrhagic fever, the Hb and Hct were 10 g/dL and 31%; the latter rose to 35% after fluid therapy. In some patients, the range of Hb and Hct levels was constantly low (4.3-5.8 g/dL and 15%-19%, respectively). (If dengue hemorrhagic fever is misdiagnosed, a fatal outcome may occur for thalassemic patients.) After a hemodiluted condition as in acute post-streptococcal glomerulonephritis, the respective Hb and Hct were 5.4 g/dL and 19%. These observations suggest that the instability of Hb E, especially during fever, may play an important role in the clinical manifestations of Hb E trait/Hb H disease with Hb Paksé and with Hb Constant Spring.

Adolescent↗
PubMed1987

The hemoglobin E belt at the Thailand-Kampuchea border: ethnic and environmental determinants of hemoglobin E and beta-thalassemia gene frequencies.

The frequencies of the hemoglobin E gene (HBB*E) and the beta-thalassemia gene(s) (HBB*T) were determined in 890 healthy adult males from three areas at the Thai-Kampuchean border in Northeastern Thailand. The population of the three study areas differs ethnically: area I is inhabited by Khmer-speaking people, area II has an ethnically mixed population (Tai-Lao, Soui and Khmer), and area III is predominantly Lao. In view of the topographic differences in malaria endemicity in the pre-eradication era, the probands from the three study areas were divided into subgroups "hills" and "plains" according to the location of their home villages. The frequencies of HBB*T were generally low, but the difference between the HBB*E frequencies in the "hills" (0.3295) and "plains" (0.2455) subgroups was highly significant. This is interpreted as environmental effect due to selection by malaria. A "hemoglobin E belt" with HBB*E frequencies between 0.3 and 0.35 extends along the Dangraek mountain chain at the border between Thailand and Kampuchea.

Adult↗