HbE Trait Research Articles

Effect of haematological alterations on thalassaemia investigation in HIV-1-infected Thai patients receiving antiretroviral therapy

To evaluate the effect of haematological alterations resulting from antiretroviral therapy (ART) on the diagnosis of thalassaemia carriers in HIV-1-infected Thai patients. Complete blood cell counts, osmotic fragility (OF) test and haemoglobin (Hb)-A(2) values were measured in blood samples of 52 antiretroviral-treated and 14 untreated HIV-1-infected patients. Data were analysed according to thalassaemia type and ART. Sixteen patients carried at least one of the investigated thalassaemia types and most of them (87.5%) received ART. Their red cell indices [mean corpuscular Hb (MCH), mean corpuscular Hb concentration (MCHC) and red blood cell distribution width (RDW)], OF test and Hb-A(2) values were observed within the critical criteria of each thalassaemia type. Normocytic red cells were observed in alpha-thalassaemia and Hb-E trait. Among HIV-1-infected patients who are non-thalassaemia carriers, higher values of Hb-A(2), MCH, macrocytosis and lower red cell counts were observed in the treated group. Values of RDW, MCHC and OF test for treated and untreated groups were in the normal range. Five treated patients had Hb-A(2) values within the critical criteria of beta-thalassaemia carriers but beta-thalassaemia gene mutations were not observed by polymerase chain reaction analysis. ART can alter many haematological figures. Therefore, diagnosis of thalassaemia should be evaluated carefully in combination with those parameters.

Discriminant function using red cell indices to distinguish between HbC and HbE traits.

Values for MCV, MCH, MCHC and red cell distribution width (RDW) derived from subjects with HbC and HbE traits using a Technicon H*1 automated blood count analyser were compared. Significantly higher MCH, MCHC and RDW values were found in those with HbC trait. By use of a simple discriminant function (MCHC2 x RDW/1000), 19/20 subjects with HbC trait gave a value > or = 16.3, and 20/21 subjects with HbE trait gave a value < or = 16.2. The function described may be of value as an adjunct to electrophoresis in intralaboratory quality control.

Generation of Transgenic Mice Expressing Human Hemoglobin E.

HbE (β26 Glu → Lys) is the most common pathogenic Hb variant in the world and is found with the greatest frequency in Southeast Asia. The HbE mutation at codon 26 of the βE-globin leads to an alternative splicing site, making this globin both a structural as well as a thalassemic mutation; furthermore, βE globin chains are unstable. HbE trait is asymptomatic and the HbEE genotype has only mild clinical manifestations. On the other hand, HbE/thalassemia presents a panoply of phenotypes from very severe to a mild beta/+ thalassemia. To date, there is no animal model of HbE disease. An animal model of this disorder could lead to better understanding of the effects of modifier genes and some of the pathogenic features of this disease. In addition, an animal model can facilitate the development of gene therapy. We report here the creation of four lines of transgenic mice that are PCR positive for HbE: two with founders that express high levels of HbE (32% human α, 26% human βE), one with low expression of HbE (9% human α, 8% βE), and one without detectable expression, but PCR positive. Knockouts (KOs) for mouse α and β globins have been bred into the founders. To date, the most severe mouse generated has a full KO of mouse α and a partial KO of mouse β. RBCs from all of the partial KOs generated to date have normal MCHC and minimally elevated reticulocyte counts (less than 1% greater than the C57Bl background). We previously demonstrated that HbEE RBCs are microcytic, but have normal MCHC. We found that HbE mice with full α-KO and partial β-KO, are microcytic (MCH 10.9 vs 14.2 for C57Bl and MCV 35.4 vs 47.5 for C57Bl), but have normal MCHC (MCHC 30.0 vs 30.5 for C57Bl). Smears from these mice exhibit numerous target cells that are not necessarily associated with low MCHC. As reported for human red cells containing HbE, elevated levels of hemoglobin oxidation products were detected in founder mice expressing HbE, but not in negative litter mates, and were found, at an even higher level, in partial KO mice expressing HbE. The next step will be to generate a mouse similar to the HbE/thalassemia phenotype by generating mice expressing exclusively HbE from either the lines expressing high levels of HbE or the line expressing low levels of HbE. These models will help elucidate several of the challenging features of the phenotypes described in humans and allow for the development of the potential cure or amelioration of HbE/thalassemia.

Generation of transgenic mice expressing human hemoglobin E

Hemoglobin E (HbE, ββ26 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 β 0-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 β E 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.

A study of spectrin and lipid peroxidation of red blood cell membrane in thalassaemia carrier.

The aim of the present work is to understand the lipid peroxidation of RBC membrane and the spectrin protein content of RBC membrane cytoskeleton of thalassaemic carrier state (trait) of β and hemoglobin E variant (HbE). We have measured the hemoglobin (Hb), malondialdehyde (MDA) and spectrin content of RBC membrane of thalassaemic carrier. The spectrin content (α and β band) of both β and HbE carrier was not changed than normal individuals. However, lipid peroxidation of RBC membrane was significantly increased in both β and HbE trait, and Hb level was also decreased in thalassaemic carrier. It may be assumed that oxidative damage by excess lipid peroxidation may have no role on irreversible membrane damage in β thalassaemia and HbE thalassaemia carrier.

Mean cell haemoglobin concentration in subjects with haemoglobin C, D, E and S traits

The Bayer H1 automated blood counter was used to assess the MCHC values of 40 nonanaemic patients with HbC trait, 21 with HbD trait, 23 with HbE trait and 69 with HbS trait. These were compared with values from controls with a normal Hb phenotype. Values were significantly higher in those with HbC, D and S traits and approached significance in those with HbE trait. In 45%, of subjects with HbC trait the MCHC value was > or = 35 g/dl. Such values may prove a useful marker for this abnormality. In a further 12 patients with HbC, D, E or S traits and coexisting iron deficiency anaemia, MCHC values were usually higher and the percentage of hypochromic cells (red cells with CHC <28 g/dl, directly measured by the H1) usually lower than values derived from controls with a normal Hb phenotype and iron deficiency anaemia of similar degree. In individuals with HbC, D, E or S traits, the MCHC and proportion of hypochromic cells are less sensitive indicators of iron lack than in subjects with a normal Hb phenotype.

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.

Electrophoretic Pattern of Hereditary Haemoglobin Disorders in Bangladesh

Background: Genetic defects of haemoglobin are the most common genetic disorders and affect around 7% of world Population, occur in tropical and sub tropical areas. â thalassaemia is more common in the Mediterranian region while á thalassaemia is more common in the Far East. Objective: To Find out the pattern of haemoglobin disorders and to evaluate and compare the diseases in study population. Methods: A total number of 210 subjects with age ranged from 2 to 72 years of both sexes were included in the study. The present study was conducted in out patient department (OPD) of Haematology, Bangabandhu Sheikh Mujib Medical University (BSMMU,) Dhaka. Bangladesh. During the period of January 2007 to December 2007, patients were selected on the basis of morphological blood film examination and Hb- electrophoresis on cellulose acetate at PH 8.6. Results: Among the 210 Subjects, thalassaemia trait were (47.14%), HbE-beta thalassaemia were 30.47%, HbE Trait 13.3%, HbE disease (5.71%) and thalassaemia major were (3.33%). Conclusion: It is evident that, Hereditary Haemoglobin disorders are quite common in Bangladesh and this disorders are inherited as autosomal recessive Mendelian pattern affecting both male and female. Key words: Electrophoretic pattern; Haemoglobin disorders. DOI: 10.3329/jdmc.v19i1.6250 J Dhaka Med. Coll. 2010; 19(1) : 39-42.