Bead-based assays to simultaneously detect multiple human inherited blood disorders associated with malaria.

BACKGROUND: Glucose-6-phosphate dehydrogenase deficiency (G6PDd), haemoglobin C (HbC) and S (HbS) are inherited blood disorders (IBD) common in populations in malaria endemic areas. All are associated to some degree with protection against clinical malaria whilst additionally G6PDd is associated with haemolysis following treatment with 8-aminoquinolines. Measuring the prevalence of these inherited blood disorders in affected populations can improve understanding of disease epidemiology. Current methodologies in epidemiological studies commonly rely on individual target amplification and visualization; here a method is presented to simultaneously detect the polymorphisms and that can be expanded to include other single nucleotide polymorphisms (SNPs) of interest. METHODS: Human DNA from whole blood samples was amplified in a novel, multiplex PCR reaction and extended with SNP-specific probes in an allele specific primer extension (ASPE) to simultaneously detect four epidemiologically important human markers including G6PD SNPs (G202A and A376G) and common haemoglobin mutations (HbS and HbC). The products were hybridized to magnetic beads and the median fluorescence intensity (MFI) was read on MAGPIX® (Luminex corp.). Genotyping data was compared to phenotypical data generated by flow cytometry and to established genotyping methods. RESULTS: Seventy-five samples from Burkina Faso (n = 75/78, 96.2%) and 58 samples from The Gambia (n = 58/61, 95.1%) had a G6PD and a HBB genotype successfully assigned by the bead-based assay. Flow cytometry data available for n = 61 samples further supported the concordance between % G6PD normal/deficient cells and genotype. CONCLUSIONS: The bead based assay compares well to alternative measures of genotyping and phenotyping for G6PD. The screening is high throughput, adaptable to inclusion of multiple targets of interest and easily standardized.

Point-of-care screening for sickle cell disease in low-resource settings: A multi-center evaluation of HemoTypeSC, a novel rapid test.

Sickle cell disease (SCD) is a common, life-threatening genetic disorder that is best managed when diagnosed early by newborn screening. However, SCD is most prevalent in low-resource regions of the world where newborn screening is rare and diagnosis at the point-of-care is challenging. In many such regions, the majority of affected children die, undiagnosed, before the age of 5 years. A rapid and affordable point-of-care test for SCD is needed. The diagnostic accuracy of HemoTypeSC, a point-of-care immunoassay, for SCD was evaluated in individuals who had SCD, hemoglobin C disease, the related carrier (trait) states, or a normal hemoglobin phenotype. Children and adults participated in low-, medium- and high-resource environments (Ghana [n = 383], Martinique [n = 46], and USA [n = 158]). Paired blood specimens were obtained for HemoTypeSC and a reference diagnostic assay. HemoTypeSC testing was performed at the site of blood collection, and the reference test was performed in a laboratory at each site. In 587 participants, across all study sites, HemoTypeSC had an overall sensitivity of 99.5% and specificity of 99.9% across all hemoglobin phenotypes. The test had 100% sensitivity and specificity for sickle cell anemia. Sensitivity and specificity for detection of normal and trait states were >99%. HemoTypeSC is an inexpensive (<$2 per test), accurate, and rapid point-of-care test that can be used in resource-limited regions with a high prevalence of SCD to provide timely diagnosis and support newborn screening programs.

Hemoglobinosis C in Morocco : A report of 111 cas.

BACKGROUND: - Hemoglobin C is a hemoglobin variant encountered worldwide. The regionswith high prevalence are West Africa and South-East Asia.The objective of this study is to report cases of hemoglobin C disease brought together during these last twelve years in the Laboratory of Biochemistry and Toxicology of RabatMilitary Hospital Mohammed V (MHIMV). METHODS: - This was a retrospective study including111 cases of hemoglobin C disease collected in the Laboratory of Biochemistry of the MHIMVover the past 12 years. A questionnairewasfulfilledwith the epidemiological data,clinical data and the results of the biological explorations. The screening of the hemoglobin variant in this study included several biochemical (hemoglobin electrophoresis at acid and alkalinepH) and hematological tests. RESULTS: - Sex-ratio was equal to 1,22. The age at the time of diagnosis ranges between 4 and 80years old, with the mean of 38. North-West regions of Morocco seem most affected. The most frequent reasons for prescription of the hemoglobin's studywere: biological abnormalities, splenomegaly and anemic syndrome. Blood smear reveals frequently anisopoikilocytosis and red blood target. The biochemical tests contribute to the diagnosis and reveal various and varied etiological groups: heterozygous A/C (75%),homozygous C/C (8%), double heterozygous S/C (9%),C/ß+-thal (6%) andC/O-Arab (2%). Conclusion - The results of the present descriptive study are in line with the literature data. The importance of genetic counseling and the installation of a national card of systematic neonatal tracking seemto be unavoidable.

Rheumatoid arthritis in patient with homozygous haemoglobin C disease.

To date, few cases of hemoglobinopathies in patients with rheumatoid arthritis (RA) have been reported (Marino and Mcdonald in J Rheumatol 17:970-972, 1990; Gladman and Bombardier in Arthritis Rheum 30:1065-1068, 1987; Michel et al. in Semin Arthritis Rheum 38:228-240, 2008). These haemoglobin diseases are associated with characteristics abnormalities of the skeleton. Haemoglobin C disease is a benign hemoglobinopathy rarely associated with skeletal disorders [Piéron et al. in la semaine des hôpitaux 57(1-2):22-25, 1981]. We report a case of RA in a 60-year-old woman with homozygous haemoglobin C disease. This coexistence may be a pure coincidence, although we discuss the difficulties with RA treatment in this case due to the unknown effect of anti-rheumatic drugs on the progression of haemoglobin C disease.

[Abnormal haemoglobins in the newborn human population of Costa Rica]. / Hemoglobinas anormales en la población neonatal de Costa Rica.

Hemoglobinopathies are hereditary autosomic recessive diseases. A total of 70 943 samples of whole blood collected by heel prick in filter paper (S&S 903) from throughout Costa Rica (October 2005-October 2006) were analyzed to detect variants of hemoglobin by the iso-electric focusing technique. Eight hundred ninety one cases presented some variant, for a frecuency of 1/79. Five cases are homozygous for hemoglobin S (sickle cell disease) and one shows the double heterozygous genotype SC. In this study the S and C variants of hemoglobin, although with some local differences, are widespread all over the country. Thus, the prevention of new cases is important through the testing of hemoglobin in the Costa Rican National Newborn Screening Program, together with a Interdisciplinary National Program of Education for the disease and carrier status (AS/AC) for patients, families and medicar personnel. This is the basis for proper genetic counseling, to improve treatment and to reduce morbi-mortality.

[Hemoglobin C disease: report of 16 Tunisian cases]. / L'hemoglobinose C: a propos de 16 cas Tunisiens.

AIM: was to provide the clinical and biological patterns hemoglobine disease in Tunisia. METHODS: This retrospective study collected to 16 cases of hemoglobin C disease : 6 homozygotic Hb C and 10 heterozygotic Hb C/beta-thalassemia. RESULTS: The clinical profile is characterized by mild hemolytic anemia (Hb = 11.7 g/dl) associated with splenomegaly and hypersplenism. Contrary to homozygous state, the Hb C/beta-thalassemia is associated with microcytosis and pseudopolycythemia. The diagnosis is based on target cells, specific intraerythrocytic Hb C crystals in blood smear and Hb C level at 100%. CONCLUSION: The Hb C disease must be considered as a benign hemoglobinopathy which is associated with a long survival without major complications.

Incidence of haemoglobinopathies detected through neonatal screening in the United Arab Emirates.

In January 2002, a pilot programme of neonatal screening for sickle cell disease was launched in the United Arab Emirates (UAE) in 3 districts of Abu Dhabi emirate. This paper reports the incidence of sickle cell diseases, other haemoglobinopathies and haemoglobinopathy carriers over a 12-month period using high performance liquid chromatography as a primary screening method. The overall incidence of sickle cell disease among 22 200 screened neonates was 0.04% (0.07% for UAE citizens and 0.02% for non-UAE citizens). The incidence of sickle cell trait was 1.1% overall (1.5% for UAE citizens and 0.8% for non-UAE citizens). Universal neonatal screening for sickle cell haemoglobin at the national level should be considered.

Hemoglobin S/C disease in a pregnant woman with crisis and fat embolization syndrome.

The complications of painful crisis and megaloblastic anemia are hallmarks of the pregnant patient with hemoglobin S/C disease. We describe here the clinical course in a patient with hemoglobin S/C disease in whom painful crisis and the fat embolization syndrom developed postpartum with severe neurologic abnormalities. Response to exchange blood transfusion was dramatic, and the patient recovered without neurologic impairment.

An automated method of differential red blood cell classification with application to the diagnosis of anemia.

A method of automated red cell analysis suitable for the rapid classification of large numbers of red cells from individual blood specimens has been developed, and preliminarily tested on normal bloods and clinically proven cases of anemias and red cell disorders. According to this method digital image processing techniques provide several features relating to shape and internal central pallor configurations of red cells. These features are used with a fully automated decision logic to rapidly provide a quantitative "red cell differential" analysis, a report of the percentage subpopulations of recognized categories of red cells. For each subpopulation, measurements of mean cell area, mean cell hemoglobin content and mean cell hemoglobin density are provided. The nine types of red cell disorders studied with this method were: (a) iron deficiency anemia, (b) the anemia of chronic disease, (c) beta-thalassemia trait, (d) sickle cell anemia, (e) hemoglobin C disease, (f) intravascular hemolysis, (g) hereditary elliptocytosis, (h) hereditary spherocytosis, and (i) megaloblastic anemia due to folic acid deficiency. Preliminary indications are that the red cell differential is useful in distinguishing between these conditions.

Automated technique for the estimation of fetal haemoglobin.

An automated alkali denaturation technique which measures fetal haemoglobin is described. This method offers greater speed and a lower standard deviation than comparable manual methods.

An assessment of techniques suitable for the diagnosis of sickle-cell disease and haemoglobin C disease in cord blood samples.

Agar gel, cellulose acetate, and starch gel electrophoresis are all capable of diagnosing sickle-cell anaemia, sickle-cell haemoglobin C disease, and haemoglobin C disease in cord blood samples. Of these three electrophoretic techniques, agar gel is the easiest to interpret.Paper electrophoresis can reliably and rapidly detect sickle haemoglobin and haemoglobin C in cord blood samples. Being incapable of differentiating foetal and normal adult haemoglobin, the value of paper electrophoresis is limited to an initial screening procedure.

Spontaneous regression (autoinfarction) of proliferative sickle retinopathy.

Of 45 patients with proliferative sickle retinopathy in stages III, IV, and V, nine patients (eight with hemoglobin SC disease, one with sickle cell thalassemia) showed spontaneous regression (autoinfarction) of retinal sea fans. One mechanism involved in autoinfarction of neovascular tissue is progressive, centripetal retraction of the anterior vascular arcade of the peripheral retina. In addition, vitreous traction on feeder vessels may result in sluggish blood flow and occlusion of these vessels, or may tear the sea fan completely away from its feeder vessels. In view of the many incidences of vitreous hemorrhages that occur in patients with proliferative retinopathy, however, we recommend treatment of neovascularization rather than prolonged observation.

Severe proliferative retinopathy as the only sign of sickle cell hemoglobin C disease.

A 48-year-old black woman developed severe bilateral hypoxic proliferative retinopathy without other clinical manifestations. The hemoglobin level was 10.6 to 11.5 g/100 ml, reticulocyte level was 2.2%, targeted and sickled red blood cells were seen on blood smears, and hemoglobins S and C were demonstrated by electrophoresis. Glucose tolerance test was normal. The development of neovascular proliferation, vitreous hemorrhage, and retinal detachment unassociated with other clinical symptoms is unusual in sickle cell hemoglobin C disease.

Prenatal diagnosis of thalassemias and hemoglobinopathies.

Thalassemia syndromes and hemoglobinopathies are of clinical genetic significance because of the severity of the sequelae associated with particular genetic constitutions in these conditions, their occurrence at high frequencies in certain populations of Mediterranean, African, and Asian origin, and the high frequency of recurrence in pregnancies of at risk families. Application of recently developed techniques of molecular genetics to the antenatal diagnosis of the most deleterious of these conditions (homozygous beta-thalassemia [Cooley's anemia], homozygous alpha-thalassemia [Barts hydrops fetalis], sickle cell anemia, and related severe homoglobinopathies) now affords parents the option to interrupt a pregnancy in which the fetus has the genetic constitution causing one of these abnormalities. The two different analytical strategies utilize fetal cells obtained by aminocentesis. In one, fetal blood is obtained either by sonographically guided placental aspiration or by aspiration from a placental vein directed by fetoscopy. Globin chain synthesis is monitored by the incorporation of radiolabelled amino acids in the isolated erythrocytes and the determination of the ratio of radioactive label incorporated into the various globin chains separated by column chromatography or electrophoresis. This technique is applicable to the antenatal diagnosis of alpha-and beta-thalassemia and to selected hemoglobinopathies. However, in the most experienced centers, fetal blood sampling is associated with a greatly increased risk of fetal loss. The other analytical approach utilizes desoxyribonucleic acid (DNA) isolated from fibroblasts to evaluate the presence of quantitatively and/or qualitatively normal DNA sequences, which constitute the structural gene(s) encoding specific globin polypeptide chains. This approach is most generally applicable to the detection of structural gene deletions as in a alpha-thalassemia; maternal and fetal risk is the same as that for conventional amniocentesis.

"In vivo" and "in vitro" demonstration of hemoglobin C crystals in non-splenectomized patients.

We studied 12 Hb C carriers: 4 homozygotic Hb CC and 8 heterozygotic. We observed the presence of free crystals in the peripheral blood of the homozygotes but in none of the heterozygotes. However, after incubation with 3% NaCl we were able to detect crystals in the heterozygotes (Hb AC and Hb SC), and in the homozygotes (Hb CC). In patient 04 (P04) less crystals formation occurred due to inhibition of the process by the presence of elevated levels of Hb F (12.2%). All the homozygotic patients had a splenomegaly of 3 to 6 fingerbreadths. We believe that the spleen wears off with time, thus allowing the passage of crystals to the peripheral blood. This finding might be associated with splenic insufficiency without a reduction of its dimensions. Finally, the finding of crystals in the peripheral blood permitted the diagnosis of Hb C obviating the need for electrophoresis.

[Prevalence of hemoglobin abnormalities in Kebili (Tunisian South)]. / Prévalence des anomalies de l'hémoglobine à Kebili (sud Tunisien).

BACKGROUND: Hemoglobin abnormalities constitute a public health problem in many countries in the world. In Tunisia, these disorders were thought to affect only the North-western population. However, the existence of hemoglobinosis concentration in Kebily in south Tunisia has been suggested by previous work. In order to estimate their frequencies, we performed a screening of hemoglobin abnormalities in the North-Kebili region, to establish a prevention program of the homozygous forms. METHODS: This screening concerned all 1st and 2nd grade primary school pupils in North Kebily. After a questionnaire, a blood sample was drawn from every child. Hemogram, sickling test, and hemoglobin electrophoresis at alkaline pH were performed for all children. Hemoglobin electrophoresis at acid pH and a specific hemoglobin A2 titration were performed for some children. RESULTS: The study concerned 1,400 children, aged between 5 and 12 years, the mean age was 7 years and 7 months +/- 10 months. Consanguinity rate and coefficient were respectively 44% and 2249 x 10(5). Endogamy was very high. The global rate of hemoglobin abnormalities was 9.4%. Drepanocytosis with a rate of 4.9% was the most frequent, followed by beta thalassemia (3.1%) and C hemoglobinosis (1.6%). These abnormalities were unequally distributed; very frequent in some localities, they were quite absent in others. CONCLUSIONS: This study revealed a hemoglobinosis concentration in Tunisia, which can be classified second after that of Beja in North-western Tunisia. The heterogeneous distribution of the hemoglobin abnormalities in North-Kebili region and the high consanguinity and endogamy rates constitute factors that promote homozygous and double heterozygous forms to arise and justify the elaboration of a preventive strategy.

Sickling syndromes in children.

The sickle cell syndromes comprise a highly diverse group of disorders which have in common the presence of sickle hemoglobin in the blood erythrocytes. The establishment of a precise diagnoffort involving both the patient and his family, but because of the important differences in prognosis and management of these various syndromes, an accurate diagnosis is of fundamental importance. Definitive therapy has not yet been developed for any of these disorders, but with the application of available forms of treatment these patients can be benefited substantially.

Hemoglobin C in association with hereditary persistence of fetal hemoglobin.

Hemoglobin C and hereditary persistence of fetal hemoglobin (HPFH) are an uncommon combination of hemoglobinopathies. Several tests are needed to verify this condition, among them hemoglobin electrophoresis and Kleihauer-Betke staining of a peripheral blood smear. Family studies are useful in delineating the genetics of the hemoglobinopathy but could not be performed in our case. In more confusing cases or with an unusual subtype, more extensive testing may be required. HPFH, by itself, is without clinical manifestations. It may be confused with other conditions; therefore, its presence in patients with hematologic symptoms requires more precise definition of the hemoglobin abnormality.