Study of nine families with haemoglobin-Lepore

Rare occurrence of hemoglobin Lepore variant in a Palestinian patient: a case report and brief literature review

Introduction

In hemoglobinopathies, a basic lesion alters the rate of globin synthesis or the structure of the globin in healthy hemoglobin (Hb). Genetic instructions are used to synthesize the polypeptide chains that make up globin chains. The kind and extent of the structural aberration of the Hb molecule are closely related to the clinical features. Hematologically, the heterozygous form of the Lepore syndrome has a pattern resembling minor thalassemia, and electrophoretically, it is characterized by aberrant Hb Lepore fractions at a rate of 5-15% and a decreased percentage of HbA and mildly increased HbF. Clinically speaking, Hb Lepore heterozygotes patients are asymptomatic and resemble the clinical picture of patients with mild thalassemia.

Case Presentation

A 28-year-old female came to our attention for assessment of generalized weakness and fatigue for a 4-month duration. Laboratory evaluation, including complete blood count, showed mild microcytic hypochromic anemia with parameters resembling the thalassemia trait. Iron profile studies were normal. Abdominal ultrasound showed mild splenomegaly. Hb electrophoresis was performed and showed an abnormal high-performance liquid chromatography pattern with an abnormal Hb band, mild elevated HbF, and mild reduction in HbA. The interpretation of the Hb electrophoresis curve suggested heterozygosity for beta chain variant Hb Lepore.

Discussion and Conclusion

Hb Lepore is one of the structural Hb variants with a characteristic fusion gene between the delta and beta chains. Hematologically, the heterozygous form of the Lepore syndrome has a pattern resembling the thalassemia trait. In Palestine, the prevalence of Hb Lepore, either homozygous or homozygous state, is unknown.

Thalassemias and Other Hemoglobinopathies in the Republic of Macedonia

This paper summarizes the results on the epidemiology and molecular basis of thalassemias and other hemoglobinopathies in the Republic of Macedonia. Over the past 40 years, population surveys of more than 22,000 participants (school children and workers) from all over the country, have shown that the average incidence of beta-thalassemia (thal) trait is 2.6%, ranging from less than 1% in the northeast to 10% in the south. The frequency of deltabeta-thal is 0.2%, while the frequency of the Swiss type of hereditary persistence of fetal hemoglobin (HPFH) is 0.3%. Screening of 9,619 newborns has shown that the frequency of alpha-thal trait is 1.5%, of which alpha-thal-2 is 1.45% and alpha-thal-1 is 0.05%. The molecular basis of the different forms of beta-thal and other hemoglobinopathies has been completely defined. Among the Macedonians, over 450 beta-thal chromosomes have been studied. Fifteen different beta-thal mutations have been detected, four of which [IVS-I-110 (G-->A), IVS-I-6 (T-->C), IVS-I-1 (G-->A), codon 39 (C-->T)] account for 85% of all beta-thal chromosomes. Among the Albanians, 48 beta-thal chromosomes have been studied. Eight different mutations have been detected, four of which [codon 39, -30 (T-->A), IVS-I-110, IVS-I-1] account for 85% of all beta-thal chromosomes. Four new mutations [-101 (C-->A), -87 (C-->G), -30, polyadenylation signal (poly A) (AATAAA-->AATGAA)] have been characterized. Molecular analyses of DNA from over 20 unrelated cases with deltabeta-thal have shown that this condition is caused by a 13 kb deletion (Sicilian type); in two families a deletion of 18 to 23 kb (Macedonian type of deltabeta-thal) was discovered. Molecular analyses of alpha-thal in the Republic of Macedonia have shown the following types of molecular defects: 20.5 kb deletion, 17.5 kb deletion, 3.7 kb deletion, poly A mutation (AATAAA-->AATGAA), and Hb Icaria [alpha142, Term-->Lys, TAA-->AAA (alpha2)]. The incidence of abnormal hemoglobins (Hbs) in the Republic of Macedonia is 0.4%. Three different alpha chain variants among 10 families, seven different beta chain variants among 33 families, two gamma chain variants in two newborns, one variant with an extended alpha chain, and Hb Lepore among 105 families, have been observed. Structural analysis of numerous cases with Hb Lepore showed that the variant was of the Washington-Boston type.

Thalassemias and Other Hemoglobinopathies in Former Yugoslavia

This review summarizes our results on the epidemiology and molecular basis of thalassemias and other hemoglobinopathies in the republics and provinces of the Former Yugoslavia. Over the past 40 years, surveys of more than 37,000 school children and more than 1,600 adults, from all over Former Yugoslavia, except Slovenia, have shown an average incidence of β-thalassemia (β-thal) trait of 1.2%, ranging from 2.9% in the south (Macedonia) to 0.8% in the northwest (Croatia). The frequency of δβ-thal was 0.2%, while that of Swiss type hereditary persistence of fetal hemoglobin (HPFH) was 0.4%. Screening of 12,680 newborns has shown that the frequency of α-thal trait was 1.5%. The molecular basis of the thalassemias in the populations of Former Yugoslavia has been completely defined. More than 700 β-thal chromosomes have been studied and their molecular defect was determined. In the Macedonian population, 16 different β-thal mutations were detected, four of which (IVS-I-110, G→A; IVS-I-6, T>C; IVS-I-1, G>A and codon 39, C>T) accounted for 85% of all β-thal chromosomes. In the Croatian population, 18 different β-thal alleles were detected. Four new mutations [nucleotide (nt) -87, C>A; IVS-II-850, G>C; initiation codon mutation T>C; polyadenylation signal (poly A), AATAAA>AATGAA)] and one new deletion (1605 bp), were characterized. Molecular analyses of DNA from over 50 unrelated cases with δβ-thal have shown that this condition was mainly caused by a 13 kb deletion (Sicilian type); in one family, a deletion of >18 to 23 kb (Macedonian-Turkish type), and in another, a deletion of 148 kb (Yugoslavian type of εγδβ-thal) of the β-globin gene complex, were discovered. Molecular analyses of α-thal from Former Yugoslavia revealed the following defects: the -20.5, -17.5 and -3.7 kb deletions, a 5 nt deletion, and Hb Icaria [α142, Term→Lys (TAA>TCA in α2)]. The incidence of abnormal hemoglobins (Hbs) in Former Yugoslavia was 0.3%. Five different α chain variants in 16 families, 16 different β chain variants in 61 families, one δ chain variant in one family, two types of Hb Lepore in 122 families and two γ chain variants, have been characterized.

Linkage analysis of the hemoglobin F determinant(s) in an Australian hemoglobin Lepore (Boston) kindred

Genetic determinants that influence the levels of fetal hemoglobin (Hb F) in a single Australian kindred with heterozygous Hb Lepore (Boston) were sought. There were 22 affected individuals, some of whom had high Hb F and others with Hb F levels within the normal range. Family members were typed for restriction fragment length polymorphisms (RFLPs) associated with the beta-globin gene complex and the nearby genetic markers D11S12, INS, HRAS, and PTH. Prior to linkage analysis, a cohort of 54 unrelated Hb Lepore heterozygotes was analyzed to establish the distribution of Hb F levels measured by alkaline denaturation (Hb FAD). An Hb F level of > 2.0% was used as the cutoff point for linkage analysis of the putative hereditary persistence of fetal hemoglobin (HPFH) determinant(s) in this kindred. Positive peak lod scores were obtained for the entire pedigree between the HPFH determinant and Hb Lepore (Zm+f = 2.35 at theta = 0.15) and beta-globin cluster (HBBC) (Zm+f = 2.38 at theta = 0.20) marker loci, indicating the possibility of an independent HPFH gene at some distance from the beta-globin gene cluster. However, most of these lod scores result from the non-Hb Lepore members of the family who, with one exception, do not have high Hb F, and when only those affected with Hb Lepore were analyzed the lod score values at these loci fell to small positive values (< 1.0). These data do not support an independent cosegregating HPFH determinant separate from the Hb Lepore locus in this pedigree. The results favor a pleiotropic effect of the Hb Lepore lesion itself influencing Hb F levels by genetic or environmental factors not yet elucidated.

Hemoglobinopathies in Yugoslavia: an update

This paper summarizes information on the epidemiology and molecular basis of hemoglobinopathies in Yugoslavia. Over the past 25 years, population surveys of more than 28,000 school children from all over the country, except Slovenia, have shown that the average incidence of beta-thalassemia (beta-thal) trait is 1.2%, ranging from 2.9% in the south (Macedonia) to 0.8% in the northwest (Croatia). The frequency of delta beta-thal is 0.2%, while the frequency of the Swiss type of hereditary persistence of fetal hemoglobin (HPFH) is 0.4%. Screening of 6,400 newborns has shown that the frequency of alpha-thal trait is 1.6%. The molecular basis of the different forms of beta-thal among Yugoslavians has been almost completely defined. Over 250 beta-thal chromosomes have been studied, and in over 90% the molecular defect was determined. Eighteen different beta-thal mutations have been detected, three of which (IVS-I-110, G-->A; IVS-I-6, T-->C; IVS-I-1, G-->A) account for more than 70% of all beta-thal chromosomes. Four new mutations [-87 (C-->A); IVS-II-850 (G-->C); initiation codon mutation T-->C; poly A (AATAAA-->AATGAA)] and one new deletion (1605 bp) have been characterized. Molecular analyses of DNA from over 30 unrelated cases with delta beta-thal have shown that this condition is mainly caused by a 13 kb deletion (Sicilian type); in one family a deletion of > 18 to 23 kb (Macedonian type), and in another family a deletion of 148 kb (Yugoslavian type of epsilon gamma delta beta-thal) of the globin gene complex was discovered. Limited studies of alpha-thal in Yugoslavia have shown the following types of molecular defects: approximately 20.5 kb deletion, approximately 17.5 kb deletion, -3.7 kb deletion, 5 nucleotide (nt) deletion, and Hb Icaria. The incidence of abnormal hemoglobins (Hbs) in Yugoslavia is 0.3%. Five different alpha chain variants among 21 families, 15 different beta chain variants among 53 families, one delta chain variant in one family, one variant with a deleted residue in one family, and two types of Hb Lepore among 122 families, have been observed.

Beta-thalassemia in Yugoslavia

This study concerned the evaluation of beta-thalassemia alleles in nearly 50 patients with beta-thalassemia major and in 130 -thalassemia heterozygotes using gene amplification and dot-blot hybridization with synthetic probes. Fourteen different mutations were observed; of these, three (IVS-I-110; IVS-I-6; IVS-I-1) account for some 75% of all beta-thalassemia alleles. Newly discovered variants, i.e. T----C in the initiation codon and AATAAA----AATGAA in the poly A site were observed in a few patients. The poly A mutation with classical beta-thalassemia alleles result in thalassemia intermedia. Hb Lepore is a rather common abnormality and combinations of this variant with beta-thalassemia often result in severe disease; a search for beta-thalassemia mutations among patients affected with this disease should include an analysis to detect this hemoglobin abnormality.

Variation in clinical severity among patients with Hb Lepore-Boston-beta-thalassaemia is related to the type of beta-thalassaemia

Clinical and haematological observations, made for 10 Yugoslavian patients with the Hb Lepore-beta-thalassaemia condition, suggested a considerable variation from severe disease and complete blood transfusion dependency to a moderate, compensated, anaemia without major complications and without a need for regular blood transfusions. As the type of Hb Lepore was the same in all patients (Lepore-Boston-Washington) and an alpha-globin gene deficiency was absent, it was concluded that the type of beta-thalassaemia determined the severity of the disease. Six patients with severe disease had one of the following three beta-thalassaemia determinants: IVS-1 position 110 G----A, exon 2 codon 39 C----T, and IVS-1 position 1 G----A, while the three patients with mild disease had the Portuguese type of thalassaemia which is caused by the T----C substitution at position 6 of the IVS-1. In one patient with severe disease the beta-thalassaemia determinant remained unknown. Our observations are consistent with those made for thalassaemia patients with a homozygosity for these determinants.

New clinical and biochemical findings from 235 patients with hemoglobin Lepore

The study of 76 Leporian families with 214 heterozygous, 9 homozygous, and 12 combinations with different type of thalassemia has allowed the authors to discuss three points: (1) The homozygous condition for Hb Lepore was until now found only in 19 people worldwide. The affirmation that this state is always similar to classic Cooley's anemia cannot be confirmed by us because the majority of our patients did not have a very severe anemia and they are still alive and in a fairly good condition. Splenectomy is always useful. In two of our patients it was found that the ratios between delta + beta and alpha mRNA agreed well with the delta beta/alpha chain biosynthetic ratio. (2) Two new forms of combined Leporian conditions were investigated. These are the combinations of Hb Lepore with delta beta thalassemia and a variant of beta thalassemia, namely, the isolated-high-Hb-A2 beta thalassemia. Both diseases present the same Hb pattern as that of homozygous Hb Lepore. Both presented a mild course also. (3) The multiform and very large experience (more than 5000 cases of genotypical hemoglobinopathies observed in the last 20 years) led us to observe that in carriers of Hb Lepore there was frequently the concomitance of malignancies, especially hemolymphoblastoses. In fact, the risk of such malignancies in the Hb Lepore carriers is 10 times higher than for thalassemics. The explanation of this finding is uncertain. It is possible, however, that the peculiar abnormality of Hb Lepore may be related to malignancy.

Haemoglobin Lepore trait: haematological and structural studies on the Italian population

Haematological data on 59 heterozygotes for haemoglobin (Hb) Lepore and 10 double heterozygotes for Hb Lepore and beta thalassaemia from 36 Italian families are reported. The red cell indices are defined and compared with those of groups of non-thalassaemic and beta thalassaemic subjects of comparable number, age and sex distribution. The relative level of each haemoglobin fraction and the absolute production of single polypeptide chains are calculated in order to compare the expression of the non-alpha chain genes in Hb Lepore trait and beta thalassaemia. Structural studies demonstrate that the haemoglobin Lepore is of the Boston type (delta 87 beta 116) in all subjects, confirming that this type of fusion variant is probably the only one which occurs in Mediterranean populations. The distribution and incidence of the Lepore haemoglobinopathy are discussed.

Hemoglobins Lepore and anti-Lepore

The structure, properties, genetics, and clinical and biochemical expression of hemoglobins Lepore (deltabeta) and anti-Lepore (betadelta) are described. In addition to the three Lepore variants (Lepore Hollandia, Lepore Baltimore and Lepore Washington) at least four anti-Lepore variants (Miyada, P Nilotic (P Congo), Coventry and Lincoln Park) are known at the present time. All known hemoglobins Lepore and anti-Lepore are products of non-homologous crossing-over between the delta and the beta genes. Although the Hb Lepore condition is expressed phenotypically and clinically as beta thalassemia, the presence of about 10% of Hb Lepore distinguishes the condition hematologically from beta thalassemia. Data on the hematological and biochemical expression of this hemoglobinopathy are presented. In contrast to the anemia in the Lepore condition, there is no phenotypic evidence of thalassemia in persons with hemoglobin anti-Lepore, because no beta chain deficiency accompanies the latter condition. Although no adequate explanation has been advanced concerning the factors which maintain a low synthesis of the Lepore and anti-Lepore chains, it has been suggested that multiple rare codons may introduce rate-limiting steps or that the deltabeta and betadelta mRNAs may be unstable. Data on the geographical distribution and structural identification of Hb Lepore are presented.

Haemoglobin LeporeBoston in a Turkish family

Haemoglobin Lepore was demonstrated in four members of a Turkish family. It was found in the heterozygote state and was associated with erythrocyte morphology similar to that observed in the beta thalassaemia trait. The average concentration of haemoglobin Lepore was 8.1% of the total haemoglobin. Structural analysis showed that the Lepore haemoglobin was the LeporeBoston type. This is the first reported instance of the occurrence of haemoglobin Lepore in Turkey.

Recent developments in foetal haemoglobin research

There have been numerous new contributions to the knowledge of foetal haemoglobin over the last few years. It is, therefore, timely to review them together. They throw light on the arrangement on the chromosome of non-alpha chain genes, and on the condition generally known as Hereditary Persistence of Foetal Haemoglobin (HPFH) and have contributed to other aspects of human ontogeny and physiology.

Haemoglobin Lepore in Cyprus

Structural analysis documented the presence of haemoglobin LeporeWashington (=LeporeBoston) in a Greek Cypriot family and provided further evidence that, of the various types of Lepore mutants, only one is common in the Mediterranean area. Two individuals in this family were heterozygous for both Hb Lepore and beta thalassaemia, but they exhibited striking differences in the clinical severity and course of the disease. The data illustrate that additional environmental or genetic factors play roles in determining or modifying the pathophysiological consequences of highly specific molecular defects and, thus, their ultimate clinical phenotypes.

Haemoglobin Lepore Boston and elliptocytosis in a family of Indonesian-German ancestry

A family is presented in which Hb Lepore Boston was found in six individuals over three generations. The gene must have had its origin either in Java (Indonesia) or in what is now the Federal Republic of Germany. The haemoglobin was characterized by amino-acid analysis of the six tryptic peptides that have a different composition in the beta- and the delta-chain. The ratio of glycine to alanine in position 136 of the fetal haemoglobin, which was somewhat raised in the Hb Lepore carriers, averaged 31:39. In addition an elliptocytosis gene was found, which was inherited independently from Hb Lepore; the simultaneous presence of elliptocytosis in three family members did not seem to aggravate the mild anaemia caused by Hb Lepore.