Epidemiology of haemoglobin disorders in Europe: an overview.

OBJECTIVE: As a result of global population movements, haemoglobin disorders (thalassaemias and sickle cell disorders) are increasingly common in the formerly non-indigenous countries of Northern and Western Europe and in the indigenous countries of Southern Europe. This article presents an overview of the changing picture and a method for assessing service needs. METHOD: Data on country of birth or ethnic origin of residents are adjusted to obtain the estimated proportions of residents and births in non-indigenous groups at risk for haemoglobin disorders in European countries. The results are combined with prevalence data in each country of origin to obtain country prevalence estimates. Service indicators (annual tests or other interventions required to ensure equitable delivery of treatment and prevention) are then derived by country. RESULTS: Haemoglobin disorders now occur at comparable frequency throughout Northern, Western and Southern Europe. Annually, there are more affected conceptions in Northern and Western than in Southern Europe, and sickle cell disorders are more common than thalassaemias. There is growing need for health policy-makers to support motivated professionals working to develop optimal patient care, carrier diagnosis, genetic counselling and access to prenatal diagnosis throughout the Region. CONCLUSION: There is a strong case for pan-European collaboration on haemoglobin disorders to share policies, standards and the instruments required to support them. These include methods for needs assessment, service standards, education and information strategies and materials, and methods for evaluating service delivery.

[Good practices for the study of hemoglobin]. / Bonnes pratiques de l'étude de l'hémoglobine.

Hemoglobinopathies have become a significant national health problem in France. The biologists have a pivotal role in the genetic diagnoses. Although sickle cell disease (SCD) is the most frequent abnormality found: not less than 200 new cases are observed each year at birth, many other globin gene variations are found in the various ethnic groups. Since 1995 a neonatal sickle cell screening program has been established for at risk newborns. This programme is supported by the "Association française de dépistage et prévention des handicaps de l'enfant" (AFDPHE). The characterization of hemoglobin genetic variations requires a comprehensive set of laboratory techniques for which we specify here main clinical and technical recommendations.

[Beta-thalassemia in metropolitan France]. / Les beta-thalassémies en France métropolitaine.

OBJECTIVES: Update the data collected in 1990 in order to assess the distribution and management of thalassemic patients presently living in Metropolitan France. METHODS: A survey conducted in France in the clinical and biological departments of haematology permitted collection of epidemiological, clinical and biological data in a population of thalassemic patients followed-up in metropolitan France. RESULTS: Analysis of the replies revealed a total of 362 thalassemia with 249 beta-thalassemia major, 81 beta-thalassemia intermedia and 32 E-beta thalassemia. These patients predominated in the East of France and in the large cities. The total number of patients has remained stable over the last decade and new cases are decreasing. Among the 249 patients presenting with a ss-thalassemia major, 42 had received a bone marrow graft, whereas 207 were systematically transfused and 189 regularly underwent iron chelating. COMMENTS: Management is standardised and efficient but could be improved on with regard to iron chelating therapy.

Outcome of a school screening programme for carriers of haemoglobin disease.

OBJECTIVES: To assess the impact of a screening programme for haemoglobinopathies which was organised from 1978 to 1985 in high secondary schools of the Marseille region. METHODS: Several variables that reflected the influence of this preventive programme on the uptake of prenatal diagnosis were investigated. To evaluate the partner's uptake for the testing, a letter was sent, together with an anonymous questionnaire, to all the haemoglobin carriers detected in this programme. To evaluate the number of prenatal diagnoses, the charts of all couples from the Marseille area who underwent genetic counselling for haemoglobinopathies were compiled. The number of affected children born between 1980 to 2000 was recorded, and the cases in which one of the parents had previously been screened at school were noted. RESULTS: Half of the carriers replied to the questionnaire: 86% knew that they have to test their partner. Six carrier couples were identified, four asked for genetic counselling and requested eight prenatal diagnoses, two couples did not request genetic counselling and have had two affected children. CONCLUSIONS: Despite the time lapse between screening, informing, and pregnancy (mean 15 years), the information was well conserved and resulted in testing of the partner. The screening programme was effective in motivating requests for prenatal diagnosis.

A novel mechanism for thalassaemia intermedia.

Thalassaemia intermedia is a moderate form of thalassaemia resulting from various genetic defects. We report an undescribed mechanism leading to this condition: a somatic deletion of the beta-globin gene in the haemopoietic lineage of a heterozygous beta-thalassaemic patient. We did molecular studies and haemoglobin analysis of the patient and his parents. We found that the deletion gives rise to a mosaic of cells with either one or no functional beta-globin gene and it extends to a region of frequent loss of heterozygosity called LOH11A, which is located close to the beta-globin locus. Thus, loss of heterozygosity can be a cause of non-malignant genetic disease.

[Glucose-6-phosphate dehydrogenase et neonatal jaundice]. / Déficit en glucose-6-phosphate déshydrogénase et ictère néonatal.

OBJECTIVE: Since 1986, quantification of G6PD activity has been a routine test for all babies born at the public maternity hospitals of Marseilles. The objective of our study was to determine the prevalence of G6PD deficiency in the population tested and to evaluate the relative risk of neonatal jaundice in newborns with G6PD deficiency. METHODS: Neonatal screening is performed on cord blood by spectrophotometric measurements of G6PD activity. A group of 7779 newborns was studied retrospectively. The occurrence of neonatal jaundice was evaluated in 85 children with G6PD deficiency and compared to 85 children with normal G6PD activity. RESULTS: The incidence of G6PD deficiency in male newborns was found to be 2.1%. The relative risk for neonatal jaundice in the G6PD deficient population compared to the non-deficient population is estimated to be 2.6. CONCLUSION: Neonatal jaundice with pathological hyperbilirubinemia develops more frequently in cases of G6PD deficiency. The early characterization of G6PD activity provides an etiological diagnosis for neonatal jaundice, as well as the opportunity to give the newborn's family information concerning hemolytic crisis prevention.

Two new Ggamma chain variants: Hb F-clamart [gamma17(A14)Lys-->Asn] and Hb F-Ouled Rabah [gamma19(B1)Asn-->Lys].

Two new fetal hemoglobin variants affecting the Ggamma chain are reported. Hb F-Clamart was found during investigation of a French newborn who presented with a mild microcytemia. The second variant was found during neonatal screening for hemoglobinopathies of 30,000 babies from a population-at-risk living in the Paris region. It was named Hb F-Ouled Rabah because its structural modification and ethnic distribution is similar to that of Hb D-Ouled Rabah [beta19(B1)Asn-->Lys]. Hb F-Ouled Rabah is clinically silent and occurs at a frequency of ca. 0.1% in newborns originating from Maghreb. Structural characterization of both variants was done by protein chemistry methods, including amino acids analysis and mass spectrometry.

Molecular basis of haemoglobinopathies and G6PD deficiency in the Comorian population.

INTRODUCTION: The Comoro archipelago is characterised by a high prevalence of red cell genetic disorders such as G6PD deficiency and haemoglobinopathies, being a region endemic for malaria. Over the last 15 years, the city of Marseilles in France has become the main destination for Comorian immigrants. This Comorian community includes patients with sickle cell disease, sickle cell/beta-thalassaemia trait, thalassaemias and G6PD deficiency. MATERIALS AND METHODS: Allele frequencies for haemoglobin S, beta-thalassaemia and G6PD deficiency were determined from neonatal and prenatal screenings of the Comorian community. Haemoglobin fractions were detected by isoelectrofocalisation, and the quantitation of HbS, HbA, HbA(2) and HbF was performed by cation exchange high performance liquid chromatography. The molecular study involved 31 alleles carrying the betaS mutation (Cd 6 [A-->T]), six beta-thalassaemic alleles and 17 G6PD-deficient alleles, selected from a group of carriers or affected subjects. RESULTS: Allele frequencies were 3% for haemoglobin S, 1% for beta-thalassaemia trait and 9.5% for G6PD deficiency. Molecular analysis had revealed that the African alleles are predominant, being present in almost all the subjects studied. Mediterranean alleles were found for all the beta-thalassaemia mutations and for three G6PD chromosomes out of 17. CONCLUSION: These data are consistent with the mixed Arab and African origin of the population of the Comoro Islands, and are of clinical interest in prenatal and newborn screening plans.

Characterization of a new polymorphism, IVS-I-108 (T-->C), and a new beta-thalassemia mutation, -27 (A-->T), discovered in the course of a prenatal diagnosis.

We report two new substitutions, IVS-I-108 (T-->C) and -27 (A-->T), identified in a couple at risk for beta-thalassemia. One is of Iranian origin and presents with two mutations: a new substitution of T-->C at nucleotide IVS-I-108, which is a silent polymorphism, and a previously described beta-thalassemia mutation at nucleotide -28 (A-->C). The other is from the island of Corsica, the only place in France where beta-thalassemia is endemic. He presents a new substitution of A-->T at nucleotide -27 in the TATA box, which was also found in several members of his family with the beta-thalassemia trait. The fetus was found to have inherited both these novel mutations.

Serum ferritin, desferrioxamine, and evolution of HIV-1 infection in thalassemic patients.

To study the respective roles of mean serum ferritin level and the mean desferrioxamine (DFX) dose on progression of HIV-1 infection, data from 49 HIV-seropositive thalassemic patients were analyzed using a Cox proportional hazards model including known confounding variables. Nine years after seroconversion, 10% of those who had been prescribed >40 mg/kg of DFX daily had entered stage IV versus 39% of those who had been prescribed a lower dose. Patients with ferritin level >1935 g/L entered stage IV more rapidly than those with a lower level (31% versus 16%). In multivariate analysis, the ferritin level was found to be an independent predictor of progression of HIV disease, whereas the mean daily dose of DFX was not. Similar results were obtained when death was the endpoint. Our results support a hypothesis that was recently expressed, that iron overload could be associated with a more rapid progression of HIV-1 infection.

Hb Bruxelles, deletion of Phebeta42, shows a low oxygen affinity and low cooperativity of ligand binding.

Functional studies of partially purified hemoglobin (Hb) Bruxelles, Phebeta42 (CD1) --> 0 indicate a major shift in the allosteric equilibrium toward the deoxy (T state) conformation. While Hb A shows a roughly symmetrical oxygenation curve with maximum cooperativity near half-saturation, Hb Bruxelles shows mainly properties of the low affinity (T state) form. The oxygen equilibrium curves for purified (>80%) Hb Bruxelles show little cooperativity and a P50 (without 2,3-diphosphoglycerate) about twice that of Hb A. The low cooperativity for Hb Bruxelles is partially compensated by an increase in oxygen affinity of the deoxy conformation and a lower 2,3-diphosphoglycerate effect. The beta chains of normal Hb have consecutive phenylalanine residues at positions 41 and 42. DNA sequencing studies of Hb Bruxelles showed a deletion of the codon TTT, which corresponds to residue Phe42. The CO rebinding kinetics after flash photolysis show mainly the slow phase, characteristic of CO binding to the deoxy conformation. In phosphate buffer at pH 7, the slow phase dominates even at low photolysis levels, where the main reaction is ligand binding to the triply liganded form. This indicates a switchover point, from the deoxy to oxy conformation, occurring beyond three ligands for Hb Bruxelles. There are few natural mutants that show a change in the oxygen affinity and cooperativity as large as that observed for Hb Bruxelles.

Priapism following splenectomy in an unstable hemoglobin: hemoglobin Olmsted beta 141 (H19) Leu-->Arg.

We report a case of severe priapism occurring in a patient with an unstable hemoglobin, Hb Olmsted (beta 141 Leu-->Arg) This is a rare hemoglobin variant, which until now has been reported only once. The clinical course of the 12-year-old boy was characterized by severe hemolytic anemia leading to splenectomy and cholecystectomy at the of 3.5 years. The priapism occurred 8 years after splenectomy, during a hemolytic febrile episode and required aspiration of the corpora cavernosa. This report raises the question of the benefit of splenectomy in patients suffering from a chronic hemolytic anemia such as that due to an unstable hemoglobin. This treatment lowers the frequency and the severity of acute hemolytic attacks, but several cases of vascular complications have been reported after splenectomy.

[Genetic hemoglobin diseases. Prevention at centers for family planning and education of maternal-child protection in Marseille]. / Maladies génétiques de l'hémoglobine. Prévention dans les centres de planification et d'éducation familiale de la protection maternelle et infantile à Marseille.

OBJECTIVES: Diseases due to inherited hemoglobin disorders represent serious medical, social, and economic problems in the region of Marseille. The only effective treatment for such diseases is allogenic bone marrow transplantation. About 200 patients with either thalassemia, sickle cell or sickle cell-beta thalassemic diseases are regularly seen in local hospitals. All of these patients come from parts of the world where genetic hemoglobin disorders are endemic. METHODS: At this time, the only approach for reducing the number of affected children born is preventive. This depends upon education, the detection of carriers, genetic counselling and sometimes, prenatal diagnosis. We have organised a program of prevention supported by a grant from the DISS (Direction des Interventions Sociales et Sanitaires) in the context of visits made to the PMI (Prevention Maternelle et Infantile). This initiative concerns women presenting for consultations for three reasons: for a prenuptial check-up, for a pregnancy, and for prescription of contraceptives. RESULTS: In each of these three situations a check-up is obligatory and, for natives of countries where hemoglobin disorders are common, a hemoglobin test is recommended. If this test reveals an abnormality, the partner or husband is also tested, if he is willing. Couples who are both carriers are given genetic counselling. CONCLUSION: This preventive initiative has yielded valuable results so we hope to follow-up on the approach and extend it to other centers. Such screening, based upon the geographic origins of patients, can be implemented in the course of a consultation by any doctor.

[Epidemiology of genetic hemoglobin diseases in metropolitan France]. / Epidémiologie des maladies génétiques de l'hémoglobine en France métropolitaine.

The number of subjects with heterozygous beta-thalassaemia and sickle-cell anaemia in metropolitan France can be evaluated by the distribution of populations originating from countries with a high prevalence of genetic haemoglobinopathies. Taking into account the movements of these populations observed since the 1982 census, the current prevalences of beta-thalassaemic and drepanocytic traits are higher than the figures of 180,000 and 130,000 respectively found at that date. On the other hand, it appears from episodic screenings performed during the last few years that the percentage of subjects with heterozygous beta-thalassaemia is 3.09% in Corsica, 0.77% in school-age population in the Marseille area, and 0.72% in the general population of Marseille, Toulon and Nice. In 1992, the number of patients with heterozygous beta-thalassaemia and with major sickle-cell syndrome is estimated at 250-350 and 1000-3000 respectively. Patients with sickle-cell anemia predominate in the Paris area, whereas those with heterozygous beta-thalassemia predominate in the provinces, notably in the Provence-Côte d'Azur and Corsica regions.