Hemoglobina Denver, una causa de desaturación en oximetría de pulso. Reporte de caso en un paciente pediátrico / Hemoglobin Denver, a cause of desaturated pulse oximetry. A pediatric case report

Las hemoglobinopatías son trastornos genéticos que afectan a la molécula de hemoglobina (Hb). Las mutaciones en las cadenas a o b que alteran el tetrámero de Hb pueden modificar la capacidad de la molécula para unirse al oxígeno. Las hemoglobinopatías con baja afinidad al oxígeno pueden presentarse con cianosis y una lectura alterada de la oximetría de pulso, lo que lleva a pruebas innecesarias y, a veces, invasivas para descartar afecciones cardiovasculares y respiratorias. En el siguiente reporte de caso, presentamos a una paciente pediátrica, asintomática, que se presentó a la consulta por detección de desaturación en oximetría de pulso. Las pruebas de laboratorio iniciales mostraron una anemia normocítica, normocrómica. Las muestras de gas venoso demostraron una p50 elevada. Después de extensas herramientas de diagnóstico, se diagnosticó una variante de Hb con baja afinidad al oxígeno, Hb Denver.

Hemoglobinopathies are genetic disorders that affect the hemoglobin (Hb) molecule. Mutations in the alpha or beta chains altering the Hb tetramer may modify the molecule's oxygen-binding capacity. Hemoglobinopathies with low oxygen affinity may occur with cyanosis and an altered pulse oximetry reading, leading to unnecessary and sometimes invasive tests to rule out cardiovascular and respiratory conditions. In the case report described here, we present an asymptomatic pediatric patient who consulted for desaturated pulse oximetry. Her initial laboratory tests showed normocytic, normochromic anemia. Venous blood gas samples showed an elevated p50. After using extensive diagnostic tools, a variant of Hb with low oxygen affinity was diagnosed: Hb Denver.

Causes of Abnormal Hemoglobin Electrophoresis / 中国实验血液学杂志

OBJECTIVE@#To investigate the possible causes of abnormal hemoglobin electrophoresis results.@*METHODS@#The hemoglobin electrophoresis results of 5 696 patients in the First Affiliated Hospital of Chengdu Medical College from September 2018 to July 2021 were collected, and the abnormal results and clinical significance were analyzed.@*RESULTS@#The results of 486 patients (accounting for 8.53%) were abnormal, of which 300 cases had increased HbA2, 135 cases had decreased HbA2, 44 cases had increased F alone, and 7 cases had abnormal hemoglobin bands. Among the 486 patients, 246 patients were thalassemia gene positive (the positive rate was 50.62%), including 29 cases of α thalassemia, 208 cases of β thalassemia and 9 cases of αβ thalassemia. Among the patients with elevated HbA2, 68.67% were detected β thalassemia, 3.00% αβ thalassemia, 9.33% were suspected to be caused by macrocytosis, 6.33% by thyroid dysfunction, and 12.67% by uncertainty of the method. Among the patients with reduced HbA2, 21.48% were detected α thalassemia, 60.00% iron deficiency anemia, 8.15% were suspected to be caused by thyroid dysfunction, and 10.37% by uncertainty of the method. Among the patients with elevated F alone, the results of thalassemia gene detection were negative, 40.91% of them were suspected to be caused by macrocytosis, 27.27% by hereditary persistence of fetal hemoglobin, 29.55% by special physiological condition of pregnant women, and 2.27% by hyperthyroidism. Abnormal hemoglobin bands were detected in 7 patients, including 4 cases of hemoglobin D, 2 cases of hemoglobin E, and 1 case of hemoglobin J.@*CONCLUSION@#Thalassemia, iron deficiency anemia, macrocytosis such as megaloblastic anemia and non-severe aplastic anemia, thyroid dysfunction, hereditary persistence of fetal hemoglobin, abnormal hemoglobin diseases, the uncertainty of the method are all important causes of abnormal hemoglobin electrophoresis results. In clinical work, the patient's indicators should be comprehensively analyzed to determine the possible cause.

HbA1c levels in individuals heterozygous for hemoglobin variants / Dosagem de hemoglobina glicada em heterozigotos para hemoglobinas variantes

Summary Objective: To evaluate the levels of glycated hemoglobin (HbA1c) in patients heterozygous for hemoglobin variants and compare the results of this test with those of a control group. Method: This was an experimental study based on the comparison of HbA1c tests in two different populations, with a test group represented by individuals heterozygous for hemoglobin variants (AS and AC) and a control group consisting of people with electrophoretic profile AA. The two populations were required to meet the following inclusion criteria: Normal levels of fasting glucose, hemoglobin, urea and triglycerides, bilirubin > 20 mg/dL and non-use of acetylsalicylic acid. 50 heterozygous subjects and 50 controls were evaluated between August 2013 and May 2014. The comparison of HbA1c levels between heterozygous individuals and control subjects was performed based on standard deviation, mean and G-Test. Results: The study assessed a test group and a control group, both with 39 adults and 11 children. The mean among heterozygous adults for HbA1c was 5.0%, while the control group showed a rate of 5.74%. Heterozygous children presented mean HbA1c at 5.11%, while the controls were at 5.78%. G-Test yielded p=0.93 for children and p=0.89 for adults. Conclusion: Our study evaluated HbA1c using ion exchange chromatography resins, and the patients heterozygous for hemoglobin variants showed no significant difference from the control group.

Resumo Objetivo: Avaliar os níveis de hemoglobina glicada em pacientes heterozigotos para hemoglobinas variantes e comparar os resultados deste exame com grupo controle. Método: Trata-se de um estudo experimental, baseado na comparação do exame de hemoglobina glicada de duas populações diferentes, sendo um grupo teste, representado por indivíduos heterozigóticos para hemoglobinas variantes (AS e AC) e um grupo controle, constituído por pessoas com perfil eletroforético AA. As duas populações verificadas devem obedecer ao critério de inclusão: glicemia de jejum, hemoglobina, ureia e triglicérides normais, bilirrubina > 20 mg/dL e não fazer uso de ácido acetilsalicílico. Foram avaliados 50 indivíduos heterozigotos e 50 controles no período de agosto de 2013 a maio de 2014. A comparação dos valores de hemoglobina glicada entre indivíduos heterozigóticos e controle foi realizada por meio do desvio padrão, média e teste G. Resultados: O estudo analisou um grupo teste e um grupo controle, ambos com 39 adultos e 11 crianças. A média dos adultos heterozigotos para HbA1c foi de 5,0%, o grupo controle apresentou índice de 5,7%. Já as crianças heterozigóticas obtiveram média de HbA1c de 5,11%, enquanto as normais apresentaram valores médios de 5,78%. O valor do teste G foi de p=0,9 para crianças e p=0,89 para adultos. Conclusão: Este estudo avaliou HbA1c pela metodologia de cromatografia de coluna com resinas de troca iônica, em que pacientes com heterozigoses para hemoglobinas variantes não apresentaram uma diferença significativa em relação ao grupo controle.

Hemoglobin Camperdown β104Arg→Ser Detection During Hemoglobin A(1c) Measurement via Capillary Electrophoresis

No abstract available.

Anemia hemolítica grave causada por hemoglobina Southampton: Presentación de caso clínico / Severe hemolytic anemia due to hemoglobin Southampton: Case report

Las hemoglobinopatías estructurales son variantes de la hemoglobina caracterizadas por la síntesis de una molécula cualitativamente diferente de la normal. La mayoría son inocuas, mientras que otras ocasionan cambios fisicoquímicos que determinan manifestaciones clínicas de gravedad variable. En el caso de las hemoglobinas inestables, las alteraciones reducen la solubilidad y facilitan la formación de complejos de hemoglobina desnaturalizada (cuerpos de Heinz) que precipitan, lo cual daña la membrana y destruye prematuramente al eritrocito. Hasta la actualidad se han descrito 142 hemoglobinas inestables, muchas de ellas ocasionan hemólisis crónica, que puede exacerbarse por infecciones o por la ingesta de medicamentos o drogas oxidantes. La hemoglobina Southampton (también conocida como hemoglobina Casper) es una variante inestable que resulta de la sustitución de un residuo de leucina por uno de prolina, en el codón ß106 (CTG ?CCG, como consecuencia de la mutación c.320 T>C. Presentamos una niña con anemia hemolítica grave, esplenomegalia y requerimiento transfusional debidos a hemoglobina Southampton.

Variant hemoglobins are the result of different types of mutations that occur in the globin genes. In many cases, these hemoglobinopathies are harmless, while in others they determine alterations in the physical and chemical properties raising clinical manifestations of variable severity. In the unstable hemoglobinopathies, the changes reduce solubility, inducing the formation of precipitates of denaturated hemoglobin (Heinz bodies), which damage the membrane and finally destroy the red blood cells prematurely. Up to now, more than 142 different unstable hemoglobins have been described, most of them cause chronic hemolysis, increased by infections or drugs. We report the clinical presentation of an unstable hemoglobin (hemoglobin Southampton) in a girl with severe hemolytic anemia, splenomegaly and red blood cell requirement.

Molecular characterization of hemoglobin D Punjab traits and clinical-hematological profile of the patients / Caracterização molecular dos traços de hemoglobina D Punjab e perfil clínico-hematológico dos pacientes

CONTEXT AND OBJECTIVE: Hemoglobin (Hb) D hemoglobinopathies are widespread diseases in northwestern India and usually present with mild hemolytic anemia and mild to moderate splenomegaly. The heterozygous form of Hb D is clinically silent, but coinheritance of Hb D with Hb S or beta-thalassemia produces clinically significant conditions like thalassemia intermedia of moderate severity. Under heterozygous conditions with coinheritance of alpha and beta-thalassemia, patients show a degree of clinical variability. Thus, our aim was to molecularly characterize the Hb D trait among individuals who were clinically symptomatic because of co-inheritance of alpha deletions or any beta-globin gene mutations. DESIGN AND SETTING: This was a cross-sectional study conducted in an autonomous tertiary-care hospital. METHODS: Complete blood count and red cell indices were measured using an automated cell analyzer. Quantitative assessment of hemoglobin Hb F, Hb A, Hb A2 and Hb D was performed by means of high performance liquid chromatography (HPLC). DNA extraction was done using the phenol-chloroform method. Molecular analyses on common alpha deletions and common beta mutations were done using the Gap polymerase chain reaction and Amplification Refractory Mutation System, respectively. RESULTS: We evaluated 30 patients and found clinical variation in the behavior of Hb D traits. In six patients, the Hb D traits were clinically symptomatic and behaved like those of thalassemia intermedia. Molecular characterization showed that three out of these six were IVS-1-5 positive. CONCLUSIONS: HPLC may not be the gold standard for diagnosing symptomatic Hb D Punjab traits. Hence, standard confirmation should include molecular studies.

CONTEXTO E OBJETIVO: Hemoglobinopatias da hemoglobina (Hb) D são doenças amplamente disseminadas no noroeste da Índia e geralmente se apresentam com anemia hemolítica leve e esplenomegalia leve a moderada. A forma heterozigótica de Hb D é clinicamente silenciosa, mas co-herança de Hb D com Hb S ou beta-talassemia produzem condições clinicamente significativas, como talassemia intermediária de gravidade moderada. Em condição heterozigótica com co-herança de alfa e beta-talassemia, pacientes mostram variabilidade clínica. Assim, nosso objetivo foi a caracterização molecular dos traços da Hb D em individuos clinicamente sintomáticos, devido à co-herança de deleções de alfa ou quaisquer mutações gênicas de beta-globina. TIPO DE ESTUDO E LOCAL: Estudo transversal; realizado em um hospital de cuidado terciário autônomo. MÉTODOS: Hemograma completo e índices de células vermelhas foram medidos pelo analisador automatizado de células. Avaliação quantitativa de hemoglobina Hb F, Hb A, Hb A2 e Hb D foi realizada por cromatografia líquida de alta eficiência. Extração de DNA foi feita pelo método de fenol-clorofórmio. Estudo molecular para deleções comuns de alfa e mutações comuns de beta foi feito por Gap-reação em cadeia da polimerase e amplificação refratária de mutação, respectivamente. RESULTADOS: Avaliamos 30 pacientes e verificamos variação clínica no comportamento dos traços da Hb D. Em seis pacientes, os traços da Hb D foram clinicamente sintomáticos e se comportavam como os de talassemia intermédia. A caracterização molecular mostrou que três desses seis pacientes eram IVS-1-5 positivos. CONCLUSÕES: HPLC pode não ser o padrão ouro para o diagnóstico de traços de Hb D Punjab sintomáticos. Assim, a confirmação padrão ouro deve incluir estudos moleculares.

Abnormal haemoglobins: detection & characterization.

Haemoglobin (Hb) abnormalities though quite frequent, are generally detected in populations during surveys and programmes run for prevention of Hb disorders. Several methods are now available for detection of Hb abnormalities. In this review, the following are discussed: (i) the methods used for characterization of haemoglobin disorders; (ii) the problems linked to diagnosis of thalassaemic trait; (iii) the strategy for detection of common Hb variants; and (iv) the difficulties in identification of rare variants. The differences between developing and industrialized countries for the strategies employed in the diagnosis of abnormal haemoglobins are considered. We mention the limits and pitfalls for each approach and the necessity to characterize the abnormalities using at least two different methods. The recommended strategy is to use a combination of cation-exchange high performance chromatography (CE-HPLC), capillary electrophoresis (CE) and when possible isoelectric focusing (IEF). Difficult cases may demand further investigations requiring specialized protein and/or molecular biology techniques.

Hemoglobin Yamagata: Hemoglobin Variant Detected by HbA1c Test / 대한진단검사의학회지

Hemoglobin (Hb) Yamagata is a rare Hb variant, which has been reported only twice-one case each in Japan and Korea. This variant arises from a Lys --> Asn substitution due to a mutation of AAA to AAC or AAT at codon 133 of the beta-globin gene. This study reports the third case of a patient detected with Hb Yamagata [HBB: c.399A>T; p.Lys133Asn] and discusses the effect of this variant on HbA1c measurement. This variant was detected in a 70-yr-old Korean man with diabetes mellitus during a routine follow-up. The HbA1c concentration determined using Variant ll Turbo (Bio-Rad, USA) was abnormally high at 47.9%. It was impossible to measure the HbA1c level accurately using Variant ll Thalassemia Mode (Bio-Rad, USA). However, the HbA1c levels analyzed by HLC-723 G7 (Tosoh, Japan), Cobas Integra (Roche, Switzerland) and NycoCard (Axis-Shield, Norway) were 5.0%, 8.0%, and 7.9%, respectively. This study shows that Hb Yamagata interferes with the accurate measurement of HbA1c levels in a diabetic patient. Taking these findings into consideration, we think that an immunoassay or affinity chromatography can be used as an alternate method for measuring the HbA1c level in a patient with this variant. In conclusion, a patient can be inferred to have an Hb variant if the HbA1c concentration is abnormally high or low or if there is a discrepancy between the results obtained using different methods, and if the clinical status of the patient suggests the presence of abnormal Hb. Subsequently, the HbA1c values can be determined by methods based on different principles.

HPLC studies in hemoglobinopathies.

An accurate diagnosis of beta -thalassemia carriers, homozygous patients and identification of different structural hemoglobin variants is important for epidemiological studies as well as for management and prevention of the major hemoglobin disorders. There are many electrophoretic and chromatographic approaches for estimation of HbA2 and Hb F but cation exchange HPLC (CE-HPLC)using automated dedicated machines like the Variant Hb testing system have become the method of choice for these investigations. CE-HPLC also helps in the presumptive identification of many abnormal hemoglobin variants and has been useful for both neonatal screening of sickle cell disease as well as second trimester prenatal diagnosis of thalassemia by fetal blood analysis. Other applications of HPLC in hemoglobinopathies include separation of globin chains, measuring the ratio of gamma globin chains (Ggamma/Agamma) and the recently described denaturing HPLC for detecting mutations in both alpha and beta globin genes.

Identification of hemoglobin AC heterozygote status in a Malay family: a decision between hemoglobin electrophoresis and high performance liquid chromotography.

Thalassemia is a common public health problem among Malays. Hemoglobin C (Hb C) is a hemoglobin beta variant resulting from a single base mutation at the 6th position of the beta-globin gene leading to the substitution of glycine for glutamic acid. Hb C is commonly detected in West Africans and in African American but has not been reported in Malaysia. It can be falsely diagnosed as HbE trait in the Malaysian Thalassemia Screening Program which utilizes cellulose acetate hemoglobin electrophoresis. This is the first reported case of Hb AC heterozygote status in a Malay family, with unusual splenomegaly in one of the family members.

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.

Hemoglobin I-Philadelphia [alpha 16 (A14) LYS-->GLU] heterozygote among blood donors from Brazil

We describe a heterozygous case of Hb I-Philadelphia [alpha 16 (A14) LYS-->GLU] in a blood donor from the Acre State Blood Bank, in the Brazilian Amazon region. We confirmed the mutation by electrophoretic and chromatographic methods and by DNA sequencing. A literature search showed that this is the first description of this alpha globin mutant in a Brazilian Caucasian group. We also emphasize the importance of the hemoglobin study in blood donors for the purpose of the genetic counseling and quality assurance of the blood to be transfused. Screening tests for hemoglobin mutants are also important for gathering anthropological information about the Brazilian population.

Análise dos haplótipos do gene da betaS-globina no Ceará / Analysis of betaS-globin gene haplotypes in Ceará, Brazil

No presente trabalho abordam-se vários aspectos relacionados à natureza molecular da anemia falciforme (AF), desordem hematológica de caráter hereditário. A descoberta do polimorfismo do DNA no grupamento do gene betaS, originando diferentes haplótipos da doença, permitiu ampliar o conhecimento em torno da heterogeneidade clínica observada nos pacientes falcêmicos nas mais diversas regiões do mundo. Analisaram-se os diferentes haplótipos e seus parâmetros hematológicos, presentes em um grupo de 22 pacientes naturais e procedentes do estado do Ceará. A distribuição das freqüências dos haplótipos encontrados foi de 55,9 por cento para Benin; 41,2 por cento para República Centro-Africana (CAR); e de 2,9 por cento para o haplótipo Senegal. Esses dados, em comparação com os demais estudos realizados no Brasil, mostram associação entre os seus valores para um alfa de 5 por cento (p < 0,05). Os resultados obtidos possibilitam um entendimento mais completo da fisiopatologia desta doença e da sua complexidade clínica em nosso meio, bem como permitem um conhecimento mais amplo da AF em nosso país.

Hemoglobin E-thalassaemia in a Sikh child: a case report.

Hemoglobin E is a beta chain variant that has its most clinically significant interaction with thalassaemia. The compound heterozygous state, thus produced, can result in a thalassaemia intermedia/major phenotype with affected individuals being transfusion dependent. Hemoglobin E is very common in north-east India with relatively fewer reportsfrom rest of the country. Reports of hemoglobin E in the Punjabi population are even rarer. A case of hemoglobin E-thalassaemia in a Sikh child is being presented because of its highly uncommon occurrence in natives of Punjab.

HPLC--how necessary is it for haemoglobinopathy diagnosis in India?

Cation exchange high performance liquid chromatography (HPLC) is emerging as the method of choice for the initial screening of thalassemias and haemoglobinopathies and quantification of Haemoglobins (Hbs) like HbA, HbA2 and HbF. Since it is expensive, the present study was conducted to evaluate the need for HPLC in Indian laboratories and identify situations where it would be imperative. Eighty three patients suspected to have thalassemia and haemoglobinopathies were analysed. Both HPLC and alkaline gel electrophoresis detected 14 cases of HbE syndrome and 14 cases of HbS syndrome. However of the 14 cases diagnosed as HbD syndrome by alkaline electrophoresis, eight cases were diagnosed as Hb Q India, 1 case as HbD Iran and 5 cases of HbD Punjab on HPLC. Thirty-one cases were detected to have beta heterozygous thalassemia based on the high HbA2 levels (>3.9%) and eight cases were diagnosed as beta homozygous thalassemia by both HPLC and gel electrophoresis. One of them had an unknown Hb migrating in F-A region. Her mother also had same unknown Hb variant. In view of electrophoretic migration and retention time (RT) on HPLC, possibility of HbG-San Jose was considered. HPLC being an automated instrument is highly sensitive and specific, has high resolution and helps in quantification of various haemoglobins. However in a developing country like India where economical factors play a major role in planning for management of patients, the role of HPLC is limited.

Hematological and molecular characterization of beta-thalassemia/Hb Tak compound heterozygote.

We report a case of beta-thalassemia/Hb Tak compound heterozygote. The 7 year-old Thai boy presented with plethora since birth. Hemoglobin electrophoresis showed a major band between Hb A2 and Hb F and absent Hb A. DNA sequencing study demonstrated an AC insertion at the terminal codon of the beta-globin gene. The clinical feature of polycythemia reflected a high oxygen affinity of Hb Tak.

Screening for the carriers of thalassemias and abnormal hemoglobins at the community level.

Thalassemia and abnormal hemoglobins are common genetic disorders in Southeast Asia. Thalassemia is not only an important public health problem but also a socio-economic problem of many countries in the region. The approach to deal with the thalassemic problem is to prevent and control births of the new cases. This requires an accurate identification of couple at high risk to have a thalassemic child. The diagnosis of thalassemia carriers need several tests that are not practical for screening the population at large. In this study we used two simple laboratory tests to screen for potential thalassemia carriers and hemoglobin E individuals. Three-hundred pregnant women and 40 spouses were recruited in this study. The methods were the red cell osmotic fragility (OF) screening test with 0.36% NaCl and the dichlorophenolindophenol (DCIP) precipitation test to detect Hb E and unstable hemoglobins. Standard methods for red cell indices, hemoglobin analysis and detection of alpha-thalassemia by immunological method were also performed to confirm genotypes of thalassemia. The results showed that 98 women (32.7%) were carriers of thalassemias and hemoglobin E. The number of false positive by OF test was 3.2% and by DCIP test was 0.6%. Sensitivity and specificity of OF test were 89.5% and 93.3%, respectively whereas those of DCIP test were 100%. Of the 40 couples investigated, one was found to be at risk of having beta-thalassemia/Hb E fetus. Screening techniques including one tube osmotic fragility and DCIP precipitation tests are sensitive and specific for the detection of thalassemia and unstable hemoglobins such as Hb E. The techniques are also simple, economic, rapid, and give minimal false negative result.

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.

Preventation of thalassemia in Australia.

Screening for thalassemia and other hemoglobinopathies in the major maternity hospitals in Melbourne, Australia has shown that 6% of the patient population carries a clinically significant genetic abnormality. The most common of these are beta-thalassemia (3%). HbS (1.8%), HbE (0.5%) and alpha0 thalassemia (0.4%). Approximately 60 prenatal diagnoses for the clinically significant combinations of these abnormal genes are performed annually in the 2 major centers of Melbourne and Sydney. The majority of these prenatal diagnoses are for beta-thalassemia major (65%). whilst 11% are for Bart's hydrops fetalis, 8% for HbE/beta-thalassemia. 6% for HbS/beta-thalassemia, 2% for sickle cell anemia and the remaining 8% for other combinations of thalassemia/hemoglobinopathies. Of the 178 patients with beta-thalassemia major, sickle cell disease or beta-thalassemia in combination with HbE or HbS, only 5 are less than 5 years old, reflecting both the success of the screening program and the increasing acceptance by couples of 1st trimester prenatal diagnosis.

Standardization on laboratory diagnosis of thalassemia and abnormal hemoglobin.

Thalassemia is one of the most common single gene disorders. The geographic distribution of thalassemia and abnormal hemoglobin has been known for many years. A worldwide significant spread of these abnormal genes, especially from Southeast Asia, occurred in the last two decades. This has resulted in a dramatic increase of Hb E disorders and various Southeast Asian thalassemia genotypes, which means that requests for hemoglobinopathy investigations are likely to increase in many laboratories worldwide. Hemoglobinopathy screening and diagnosis may need to be undertaken antenatally, neonatally and in certain hematological situations. The introduction of automation for hemoglobinopathy screening, including the automated cell counting and HPLC system, is an important advance in technology for hematology laboratories. The instruments need to be calibrated and standardized to get an accurate data for interpretation. Internal and external control samples are also needed. Combination of test results is usually required to achieve a proper diagnosis, which in turn, provide a self-check for each laboratory test.