Bases moleculares de alfa-talasemia en la Argentina

La α-talasemia, es uno de los desórdenes hereditarios más frecuentes mundialmente. Al presente, el diagnóstico molecular es la única herramienta que permite el diagnóstico certero. El propósito de este trabajo fue caracterizar las bases moleculares de estos síndromes en nuestro medio, y establecer relaciones genotipo-fenotipo. Mediante la complementación de distintas técnicas de biología molecular e hibridación fluorescente in situ (FISH), se logró poner en evidencia la presencia de mutaciones α-talasémicas en 145 de 184 (78.8%) pacientes estudiados con perfil hematológico compatible con α-talasemia. Dentro de este grupo, las deleciones correspondieron al defecto genético más frecuente, prevaleciendo la mutación -α3.7 en genotipos heterocigotas y homocigotas. Asimismo, en pacientes con fenotipo α0 las deleciones prevalentes fueron -MED y -CAL/CAMP. Este estudio permitió también describir una deleción de la región sub-telomérica en un paciente con α-talasemia y retraso mental. En el 7.6% de los pacientes caracterizados clínicamente como posibles α-talasémicos (microcitosis con valores de Hb A2 inferiores al 3.5%), se hallaron mutaciones β-talasémicas en estado heterocigota. Se lograron establecer perfiles hematológicos asociados a los genotipos α+ y α0 para pacientes adultos y niños. Esperamos que este trabajo pueda servir como guía para reconocer posibles portadores α-talasémicos. También permite destacar el trabajo en conjunto de médicos hematólogos, el laboratorio (bioquímico y de biología molecular) y de los médicos genetistas, con el fin de proporcionar adecuado consejo genético.

The α-thalassemia is one of the most common hereditary disorders worldwide. Currently, molecular diagnostics is the only available tool to achieve an accurate diagnosis. The purpose of this study was to characterize the molecular bases of these syndromes in our environment and to establish genotype-phenotype associations. Through a combination of different molecular techniques and fluorescent in situ hybridization (FISH),we were able to find α-thalassemic mutations in 145 of the 184 patients (78.8%) studied with hematological parameters compatible with α-thalassemia. Deletions of the a-globin genes resulted the major molecular cause of the disease, and the most frequent mutation was -α3.7, found in homozygous and heterozygous genotypes. In patients with α0 phenotypes, other prevalent mutations were -MED and -CAL/CAMP. The description of a sub-telomeric deletion in a patient with α-thalassemia and mental retardation was also achieved. β-thalassemic mutations in heterozygous state were found in 7.6% of the patients, who presented α-thalassemic clinical features (microcytosis and Hb A2 levels below 3.5%). Hematologic profiles for the α+ and α0 genotypes were established for adult and pediatric patients. Hopefully, this work will provide guidelines for the detection of possible α-thalassemic carriers. It also highlights the collaborative work of hematologists, the biochemical and molecular biology laboratory and genetists, in order to provide appropriate genetic counseling.

Hb E/beta-thalassaemia: a common & clinically diverse disorder.

Haemoglobin E-beta thalassaemia (Hb E/β-thalassaemia) is the genotype responsible for approximately one-half of all severe beta-thalassaemia worldwide. The disorder is characterized by marked clinical variability, ranging from a mild and asymptomatic anaemia to a life-threatening disorder requiring transfusions from infancy. The phenotypic variability of Hb E/β-thalassaemia and the paucity of long-term clinical data, present challenges in providing definitive recommendations for the optimal management of patients. Genetic factors influencing the severity of this disorder include the type of beta-thalassaemia mutation, the co-inheritance of alpha-thalassaemia, and polymorphisms associated with increased production of foetal haemoglobin. Other factors, including a variable increase in serum erythropoietin in response to anaemia, previous or ongoing infection with malaria, previous splenectomy and other environmental influences, may be involved. The remarkable variation, and the instability, of the clinical phenotype of Hb E beta-thalassaemia suggests that careful tailoring of treatment is required for each patient, and that therapeutic approaches should be re-assessed over-time.

A comparative study of hematological parameters of α and β thalassemias in a high prevalence zone: Saudi Arabia.

BACKGROUND AND AIMS: Saudi Arabia falls in the high prevalent zone of αα and β thalassemias. Early screening for the type of thalassemia is essential for further investigations and management. The study was carried out to differentiate the type of thalassemia based on red cell indices and other hematological parameters. MATERIALS AND METHODS: The study was carried out on 991 clinically suspected cases of thalassemias in Riyadh, Saudi Arabia. The hematological parameters were studied on Coulter STKS. Cellulose acetate hemoglobin electrophoresis and high-performance liquid chromatography (HPLC) were performed on all the blood samples. Gene deletion studies were carried out by restriction fragment length polymorphism (RFLP) technique using the restriction endonucleases Bam HI. STATISTICAL ANALYSIS: Statistical analysis was performed on SPSS 11.5 version. RESULTS: The hemoglobin electrophoresis and gene studies revealed that there were 406 (40.96%) and 59 (5.95 %) cases of β thalassemia trait and β thalassemia major respectively including adults and children. 426 cases of various deletion forms of α thalassemias were seen. Microcytosis was a common feature in β thalassemias trait and (-α/-α) and (--/αα) types of α thalassemias. MCH was a more significant distinguishing feature among thalassemias. β thalassemia major and α thalassemia (-α/αα) had almost normal hematological parameters. CONCLUSION: MCV and RBC counts are not statistically significant features for discriminating between α and β thalassemias. There is need for development of a discrimination index to differentiate between α and β thalassemias traits on the lines of discriminatory Indices available for distinguishing β thalassemias trait from iron deficiency anemia.

a talasemia no deleción en España: Índices hematológicos anormales y su estudio molecular / No Deletion a Thalassaemia in Spain: Abnormal hematological index and molecular study

Las a talasemias en la mayoría de los casos es debida a deleciones que afectan a uno o a los dos genes a, siendo poco frecuente los casos debidos a mutaciones puntuales, inserciones o deleciones de pocos pares de bases, los cuales se han denominado a talasemias no deleción. Se determinó la incidencia de la a talasemia no deleción en los pacientes con a talasemia, mediante biología molecular. Se estudiaron 517 individuos remitidos al Hospital Clínico San Carlos, centro de referencia de estudios moleculares de Talasemias en Madrid- España, entre Enero del 2001 a Diciembre del 2003, en los que se había descartado ferropenia y presentaban microcitosis, hipocromía, Hb A2, Hb F y EEF de Hbs normales. Se estudiaron los 2 tipos de a talasemia no deleción más descritas en el Mediterráneo: 1) aHph debida a la deleción de 5 bp en el IVS I y 2) aNco a un cambio en el codón de iniciación del gen. De los 517, 40 presentaban una a talasemia no deleción (7,7%). De éstos, 28 fueron positivos para aHph del gen a2, 24 en estado heterocigoto, 1 homocigoto y 3 dobles heterocigotos asociados con la deleción 3,7 kb. Los 12 restantes resultaron positivos para la aNco del gen a2, 10 heterocigotos, 1 homocigoto y 1 doble heterocigoto asociado con la deleción 4,2 kb. La a talasemia no deleción representa < 8% de los casos de a talasemia en nuestro medio. La aHph es el tipo de a talasemia no deleción más frecuente y cuyas anormalidades hematológicas son más manifiestas que las presentadas en los casos de aNco.

The a thalassaemia diseases in most cases are caused by deletions that affect one or two of the a genes, being less frequent the cases due to punctual mutations, insertions or deletions of a few pairs of bases, which have been denominated no deletion a thalassaemias. The objective of this investigation was to determine the incidence of the no deletion a thalassaemia in patients with a thalassaemia using molecular biology techniques. We studied 517 individuals of the San Carlos Hospital (Thalassemia Molecular Research Center, Madrid-Spain) between January 2001 and December 2003, in whom iron deficiency anemia had been ruled out, that presented microcytosis and hypochromia and that presented normal HbA2, HbF and EEF from normal Hbs. The two types of no deletion a thalassaemia most frequently described in the Mediterranean were studied: 1) a Hph due to deletion of 5bp in the IVS I and 2) aNco due to a change in the initiation codon of the gene. Of the 517 cases studied, 40 (7.7% of the cases) represented a no deletion a thalassaemia. Of these cases, 28 were positive for aHph of the a2 gene, 24 in the heterozygote state, one homozygote and three double heterozygotes associated with the 3,7 kb deletion. The remaining 12 cases were positive for the aNco of the a2 gene, 10 heterozygotes, one homozygote and one double heterozygote associated with the 4,2 kb deletion. The no deletion a thalassaemias represent < 8% from the cases in our environment. The aHph is the most frequent type of no deletion a thalassaemia and its haematological abnormalities are more manifest that the ones present in the cases of aNco.

Diversidade fenotípica de polimorfismos na região controladora do locus(LCR) do gene da globina beta na anemia falcifore / Phenotypic diversity of polymorphisms in the locus control region (LCR) of the beta globin gene in sickle falcifore

Os indivíduos com anemia falciforme (AF) possuem perfil clínico heterogêneo em função de fatores variados que contribuem para a modulação da doença, como a concentração de hemoglobina fetal (HbF), presença de haplótipos (HAPLO) ligados ao grupo de genes da globina beta S, talassemia alfa (TA) e mutações em genes específicos, como as localizadas nos sítios hipersensíveis a ação da DNAse I na região controladora do lócus da globina beta (LCR). O objetivo do presente estudo foi identificar subfenótipos da anemia falciforme a partir do estudo de marcadores biológicos associados aos seus portadores. As determinações hematológicas, bioquímicas e sorológicas foram realizadas na Faculdade de Farmácia da UFBA pelo uso de Kits diagnósticos e métodos automatizados. O padrão de hemoglobina foi analisado por cromatografia líquida de alto desempenho (HPLC), os haplo por PCR-RFLP e a TA por PCR. As sequências do HS-LCR foram amplificadas através da PCR e sequenciadas no ABI Prism 3100 DNA Sequencer. As análises estatísticas foram realizadas nos programas EPI INFO versão 6.04, SPSS versão 18.0 e o Prism versão 5.0. Os valores de p<0,05 foram considerados significativos para as análises realizadas. O estudo foi aprovado pelo comitê de ética em pesquisas do CPqGM-FIOCRUZ. Foram investigados 2223 indivíduos com AF, com idade entre 1-50 anos e média de 20,86 (±11,06) anos, sendo 50,70% mulheres. Valores significativos foram encontrados para os dados hematológicos e bioquímicos entre os sexos para contagem global de linfócitos nos homens (6414,85 ± 3940,70 x106/L) e mulheres (5597,81 ± 2744,24 x106/L), p= 0,003 e a contagem de reticulócitos entre os homens (7,01 ± 4,66) e mulheres (7,74 ± 5,89), p= 0,043; o colesterol de baixa densidade (LDL-c), a aspartato e alanina aminotransferases, respectivamente com p= 0,009, p= 0,029, p= 0,038 para homens e mulheres. Ao correlacionarmos eventos clínicos entre homens e mulheres, verificamos que a STA possui razão de prevalência de 1,89 para os homens (IC: 1,52-2,36, p <0,001) e de 1,59 (IC:1,06-2,39, p= 0,023) para a ocorrência de hospitalizações nesse mesmo sexo. A talassemia alfa foi realizada em 820 pacientes com 196 (23,90%) heterozigotos e 21 (2,6%) homozigotos. O total de 1872 cromossomos beta S foram estudados, sendo que os mais frequentes foram os haplótipos CAR/CAR (20,0%); Ben/Ben (25,8%) e CAR/Ben (44,2%). A correlação entre TA e dados hematológicos demonstraram resultados significativos para hemácias (Hm) (p= 0,004), volume corpuscular médio (VCM) (p= 0,015), hemoglobina corpuscular média (HCM) (p= 0,006) e plaquetas (p= 0,016) e no perfil lipídico com triglicerídeos (p= 0,001). A consulta retrospectiva aos prontuários de acompanhamento ambulatorial de 1799 pacientes com AF demonstrou que 1368 pacientes (76.04%) apresentaram pelo menos um evento vaso-oclusivo e 1475 (81.98%) tiveram pelo menos uma internação. Destes 856 (47,6%) apresentaram crise álgica; 1268 (70,5%) crises vaso-oclusivas; 115 (6,4%) Síndrome torácica aguda (STA); 53 (2,9%) dor abdominal e 24 (1,3%) dos 924 homens apresentaram priapismo. Novecentos e dezesseis (52,3%) pacientes realizaram pelo menos uma transfusão sanguínea nos dois últimos anos. O registro de infecção foi frequente em 638 (43,5%) pacientes, sendo a pneumonia a causa mais frequente, com 347 (23,6%) relatos. Cento e quinze (6,4%) pacientes foram acometidos por pelo menos um evento de AVC e 111 (6,2%) por úlcera maleolar. Quando estratificamos a idade para menor de 21 anos, a ocorrência de dactilite (síndrome mão) foi descrita em 3,5% (40) e de sequestro esplênico em 14,3% (163) nos 1141 pacientes pediátricos. A associação entre dados hematológicos.

Hemoglobin H disease in Muscat, Oman - a 5 year study

Published data indicate that Alpha thalassemia trait is prevalent in 45% of population of Sultanate of Oman. Recent unpublished data suggest that this prevalence is higher than 45%. Yet clinical suspicion or investigations into alpha-thalassemias are lacking. Moreover, Hemoglobin H disease is considered rare in Oman. We decided, therefore to look for Hemoglobin H disease and characterize the clinico-hematopathological features of the disease. Patient demographics, clinical details and detailed hematology parametry of Hemoglobin H disease cases, diagnosed by Department of Laboratory over a period of 5 years between February 2002 and January 2007 in patients presenting at Al-Nahdha Hospital and Genetic counseling unit in Muscat were compiled from hospital and laboratory records and analyzed. Twenty cases of Hemoglobin H disease in Omanis were diagnosed mainly during the second decade. 60% belonged to Al-Balushi tribe. 40% of cases presented with body pains. 35% presented with nonspecific symptoms. 50% of cases were erroneously labeled as Iron deficiency anemia. Microcytic erythrocytosis, high Red Cell Distribution Width, numerous misshapen Red Blood Cells, pseudothrombocytosis, low A2 and normal Ferritin were important diagnostic clues. Hemoglobin H inclusions in special reticulocyte smears and Hemoglobin H on HPLC or Electrophoresis were diagnostic. Hemoglobin H disease is common in Oman. The need to do HPLC, G6PD activity and Ferritin studies in all cases of anemia in Oman to avoid missing diagnosis of Hemoglobin H disease is stressed. This study is intended to create awareness about Hemoglobin H disease in order to diagnose early, treat rightly, counsel correctly and pave the path for prevention of alpha-thalassemia disease in Oman

HPLC determination of hemoglobins to establish reference values with the aid of statistics and informatics

The purpose of the present study was to establish reference values for hemoglobins (Hb) using HPLC, in samples containing normal Hb (AA), sickle cell trait without alpha-thalassemia (AS), sickle cell trait with alpha-thalassemia (ASH), sickle cell anemia (SS), and Hb SC disease (SC). The blood samples were analyzed by electrophoresis, HPLC and molecular procedures. The Hb A2 mean was 4.30 +/- 0.44% in AS, 4.18 +/- 0.42% in ASH, 3.90 +/- 1.14% in SS, and 4.39 +/- 0.35% in SC. They were similar, but above the normal range. Between the AS and ASH groups, only the amount of Hb S was higher in the AS group. The Hb S mean in the AS group was 38.54 +/- 3.01% and in the ASH it was 36.54 +/- 3.76%. In the qualitative analysis, using FastMap, distinct groups were seen: AA and SS located at opposite extremes, AS and ASH with overlapping values and intermediate distribution, SC between heterozygotes and the SS group. Hb S was confirmed by allele-specific polymerase chain reaction. The Hb values established will be available for use as a reference for the Brazilian population, drawing attention to the increased levels of Hb A2, which should be considered with caution to prevent incorrect diagnoses.

An increase of the cardiothoracic ratio leads to a diagnosis of Bart's hydrops.

BACKGROUND: Thalassemia is a common single gene disorder in Southeast Asia. a-thalassemia is a group of syndrome characterized by deficient production of the alpha-globin chain. Individuals with heterozygous alpha-thalassemia-1 are at risk of having a fetus that has Hemoglobin Bart's hydrops fetalis (Hb Bart's). Usually, when the hemoglobin electrophoresis in heterozygous alpha-thalassemia-1 is normal, the Mean Corpuscular Volume (MCV) is lowered. We report a case of increased cardiothoracic ratio that led to a diagnosis of Hb Bart's in a couple who had normal hemoglobin electrophoresis and low MCV. CASE REPORT: A 23-year-old woman, gravida 2, Para 0-0-1-0, initially presented for antenatal care at 13 weeks pregnancy. Her MCV was 67 fentolitre, DiChlorophenol-IndolPhenol (DCIP) test was negative and hemoglobin electrophoresis was normal. Her husbands MCV was 67 fentolitre, and hemoglobin electrophoresis was normal. Cardiomegaly (an increased of the cardiothoracic ratio) was detected by ultrasonogram at 25 weeks of gestation. She and her husband were comprehensively counseled after an Hb Bart's was suspected. A cordocentesis was performed and the fetal blood was tested for hemoglobin electrophoresis. The result was later known and confirmed as Hb Bart's. The couple decided to terminate the pregnancy. The induced abortion was successful and the patient was discharged on the second day after the abortion. She was well at the 4-week follow-up. CONCLUSION: A prenatal ultrasonographic screening should be conducted in couples who are suspected of being alpha-thalassemia-1 carriers when DNA study of alpha-globin gene cannot be performed. The increase of cardiothoracic ratio will help detect an early stage of Hb Bart's.

Patrón clínico y hematológico de pacientes con drepanocitosis o diagnóstico presuntivo de talasemia / Hematological and clinical profile in sickle cell or thalassemic patients

Clinical and hematological characteristics of 14 patients with sickle cell anemia; one heterozygous AS, and 7, with diagnostic of microcytic hypochromic anemia were analyzed. Hemoglobin phenotypes were identified by electrophoresis, fetal hemoglobin was quantificated for alkaline denaturation and the HbA2 for ionic exchange chromatography; -α3,7-thalassemia was detected by mutation identification using polymerase chain reaction (PCR). SS phenotype was confirmed in 10 patients, two were SSF, one was SSFA2, and one was ASF (HbF - 2%). The patient diagnosed as AS was SSF (HbF = 21%). AD-patients presented a moderate clinical course of the illness. Five microcytic hypochromic anemia patients were HbAA, one was HbAAA2 and another HbAAF; those patients present a high hematological and clinical variation, β-thalassemia was 19%. -α3,7 -thalassemia was not detected. Infection was most frequent clinical manifestation (respiratory tract infection and intestinal parasitism). These results shows that -α3,7 -thalassemia are not modulator genetic factors of clinical and hematological manifestations of patients with microcytic hypochromic anemia and sickle cell anemia. We suggest that environmental factors such as respiratory tract infection and intestinal parasitism may be affect the course of illness.

Se analizaron las características clínicas y hematológicas de 14 pacientes con diagnóstico clínico de anemia drepanocítica (AD), un heterocigoto AS con manifestaciones clínicas, y siete pacientes con diagnóstico de anemia microcítica hipocrómica resistente a tratamiento con hierro y ácido fólico. Los fenotipos hemoglobínicos fueron determinados mediante electroforesis, la cuantificación de hemoglobina fetal se realizó por desnaturalización alcalina y la hemoglobina A2 por cromatografía de intercambio iónico. La detección de -α3,7 talasemia se realizó mediante la técnica de reacción en cadena de polimerasa (PCR). Se confirmó el fenotipo SS para 10 pacientes; de los cuatro restantes, dos fueron SSF, uno SSFA2, y uno fue heterocigoto ASF (HbF = 2%). El paciente diagnosticado como heterocigoto AS resultó ser SSF (HbF = 21%). Los pacientes con AD presentaron un curso clínico moderado de la enfermedad. De los siete pacientes con anemia microcítica hipocrómica, cinco fueron HbAA, uno fue HbAAA2 y otro HbAAF; todos presentaron una alta variación hematológica y clínica. Se detectó la presencia de β-talasemia en 19% de los pacientes. No se detectó la presencia de -α3,7 -talasemia. La manifestación clínica más frecuente fue la infección (respiratoria o parasitismo intestinal). De acuerdo con estos resultados, en estos pacientes se descarta la presencia de -α3,7 -talasemia, como atenuante de las manifestaciones clínicas de la anemia drepanocítica y como factor modulador de la variabilidad clínica observada en los pacientes con anemia microcítica-hipocrómica; se sugiere que factores ambientales tales como parasitosis intestinales y enfermedades respiratorias pueden afectar el curso de la enfermedad.

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.

Hemoglobinopathies among five major ethnic groups in Karachi, Pakistan.

A brief survey of abnormal hemoglobin variants among the major ethnic groups of Karachi was conducted; 202,600 subjects were studied. Patients with low hemoglobin (Hb), low mean cell volume (MCV) and mean cell hemoglobin (MCH) including anemia, microcytosis, hypochromic hemolysis and target cells, were refered for the identification of hemoglobinopathy by molecular methods. Population screening showed that 60% had iron-deficiency anemia and 40% had hemolytic anemia, of which 20.6% was due to beta-thalassemia major, 13% beta-thalassemia trait, 5.1% sickle cell disease, 0.76% hemoglobin D Punjab (HbD Punjab), 0.32% hemoglobin C (HbC), and 0.22% hereditary persistence of fetal hemoglobin (HPFH).

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.

Alpha-Globin genes: thalassemic and structural alterations in a Brazilian population

Seven unrelated patients with hemoglobin (Hb) H disease and 27 individuals with alpha-chain structural alterations were studied to identify the alpha-globin gene mutations present in the population of Southeast Brazil. The -alpha3.7, --MED and -(alpha)20.5 deletions were investigated by PCR, whereas non-deletional alpha-thalassemia (alphaHphalpha, alphaNcoIalpha, aaNcoI, alphaIcalpha and alphaTSaudialpha) was screened with restriction enzymes and by nested PCR. Structural alterations were identified by direct DNA sequencing. Of the seven patients with Hb H disease, all of Italian descent, two had the -(alpha)20.5/-alpha3.7 genotype, one had the --MED/-alpha3.7 genotype, one had the --MED/alphaHphalpha genotype and three showed interaction of the -alpha3.7 deletion with an unusual, unidentified form of non-deletional alpha-thalassemia [-alpha3.7/(aa)T]. Among the 27 patients with structural alterations, 15 (of Italian descent) had Hb Hasharon (alpha47Asp->His) associated with the -alpha3.7 deletion, 4 (of Italian descent) were heterozygous for Hb J-Rovigo (alpha53Ala->Asp), 4 (3 Blacks and 1 Caucasian) were heterozygous for Hb Stanleyville-II (alpha78Asn->Lys) associated with the alpha+-thalassemia, 1 (Black) was heterozygous for Hb G-Pest (alpha74Asp->Asn), 1 (Caucasian) was heterozygous for Hb Kurosaki (alpha7Lys->Glu), 1 (Caucasian) was heterozygous for Hb Westmead (alpha122His->Gln), and 1 (Caucasian) was the carrier of a novel silent variant (Hb Campinas, alpha26Ala->Val). Most of the mutations found reflected the Mediterranean and African origins of the population. Hbs G-Pest and Kurosaki, very rare, and Hb Westmead, common in southern China, were initially described in individuals of ethnic origin differing from those of the carriers reported in the present study and are the first cases to be reported in the Brazilian population

Rosetting of Plasmodium falciparum required multiple components of the uninfected erythrocytes.

The mechanism of rosette formation of uninfected erythrocytes with Plasmodium falciparum-infected erythrocytes is rarely described. In this study, rosetting of uninfected normal erythrocytes with infected erythrocytes significantly reduced after treatment of the uninfected erythrocytes with neuraminidase. In contrast, the rosetting property of the infected erythrocytes was abolished by trypsinization but not by neuraminidase. The in vitro rosetting model showed that uninfected thalassemic erythrocytes poorly formed rosettes with infected normal erythrocytes when compared with normal erythrocytes of the same blood group. A rosetting parasite clone showed significant reduction in rosetting with thalassemic erythrocytes of all blood groups, however, this reduction was not obvious when the wild P. falciparum isolates were studied. These results suggest that while parasites from a single clone can rosette with uninfected erythrocytes via carbohydrate component, there is more than one type of receptor on uninfected erythrocytes involved in rosette formation with the heterogeneous populations of the wild P. falciparum isolates.

Haemoglobin disease in Bahrain

The files of twenty six children with haemoglobin H disease who presented to the paediatric clinic of salmaniya medical complex were retrospectively studied. They were clinically assessed for severity of anaemia, requirement for blood transfusion, splenic enlargement and growth parameters. There were 11 males and 15 females, and the mean age at diagnosis was 6.7 years. The mean haemoglobin was 8.1 g/dl, and the mean Hb H level was 17.4%. thirteen children required blood transfusion. Seventeen children had average growth and nine were below average, and there were no significant thalassaemic bone changes or splenomegly. These results demonstrate that haemoglobin H disease in bahraini children is phenotypically mild to moderate

Trimodal distribution of HbS levels in sickle heterozygotes--an useful predictor of the alpha-genotype for population screening.

The trimodal distribution of HbS levels in sickle heterozygotes has been used as an indirect approach to determine the prevalence of alpha-thalassaemia in different population groups. We used this approach to predict the alpha-genotypes of 124 sickle cell heterozygotes where the HbS concentration varied from 20 to 46 per cent with antimodes at 28.0 and 33.0. The alpha-genotypes in these individuals were also determined by Southern blot hybridization. We predicted homozygous (-alpha/-alpha) or heterozygous (-alpha/alpha alpha) alpha-thalassaemia-2 in 78 subjects by the trimodal distribution of HbS. However, actual genotyping showed that 75 patients had alpha-thalassaemia. Forty six of the 47 subjects with a normal alpha-globin genotype (alpha alpha/alpha alpha) could be predicted indirectly. The overall sensitivity was 100 per cent and specificity was 94.2 per cent with a positive predictive value of 96.2 per cent and negative predictive value of 100 per cent. As alpha-genotyping is very expensive and not feasible in most laboratories in India, we conclude that the trimodal distribution of HbS levels is a suitable method for screening for alpha-thalassaemia in population studies.

The influence of alpha-thalassaemia on the haematological & clinical expression of sickle cell disease in western India.

We evaluated the clinical and haematological features of 29 sickle cell anaemia patients with associated alpha-thalassaemia and 22 sickle cell homozygotes with a normal alpha-globin genotype from western India. The presence of alpha-thalassaemia resulted in significantly higher haemoglobin (Hb), haematocrit (HCT), red blood cells counts (RBC) and haemoglobin A2 (HbA2) levels but lower mean cell haemoglobin (MCH) and mean cell volume (MCV). The clinical presentation in these patients was also milder with fewer episodes of painful crisis, chest syndromes, infections, requirement of hospitalization and blood transfusions. However, splenomegaly was more common as compared to the patients with a normal alpha-globin genotype. It is evident from the present study that alpha-thalassaemia could be an important genetic factor modulating the clinical expression and haematological severity of sickle cell anaemia in this region.

Zinc and copper status of thalassemic children.

We investigated the amount of both zinc and copper in plasma, erythrocytes and hair in 11 patients with hemoglobin H disease, 59 patients with beta-thalassemia/HbE disease and 20 patients with homozygous beta-thalassemia. Plasma and hair zinc levels were found to be much lower, but erythrocyte zinc levels were higher, in thalassemic patients than in controls. The levels of copper in both plasma and erythrocytes were higher in the patients than in the controls. The mechanism with respect to the increase of the amount of both zinc and copper in erythrocytes was not clear; this result may reflect the impairment of zinc and copper utilization in tissues in the pathogenesis of these thalassemic patients.

Morphological alterations and apoptosis of endothelial cells induced by thalassemic serum in vitro.

Vascular complications such as lung thromboembolism and leg ulcer have been observed in thalassemic patients. Recently, our group has reported impaired proliferation of endothelial cells (ECs) after exposure to alpha- and beta-thalassemic sera in a culture system. This study was undertaken to detect apoptotic phenomena of ECs in the presence of alpha- and beta-thalassemic serum. ECs from normal human umbilical cord vein were exposed to 30% thalassemic serum in vitro and morphological changes were observed by using phase contrast, fluorescence and scanning electron microscopy. Such treated ECs presented morphological characteristics of apoptosis as shown by the appearance of compact cytosol, membrane blebbing, margination of nuclear matrix, condensed nuclei, and fragmented bodies. The majority of apoptotic cells was in the floating population. Similar morphological changes were also observed by treating ECs with hydrogen peroxide in the concentration range of 0.1-10 mM.