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R Galanello

Publications and source records attributed to R Galanello.

At least 73 records · Page 4Linked to original sources
PubMed1992

Normal delta-globin gene sequences in Sardinian nondeletional delta beta-thalassemia.

In order to clarify the reasons for the reduced Hb A2 levels in Sardinian delta beta-thalassemia, we characterized, both by cloning and sequence analysis and by direct sequencing of amplified DNA, the delta-globin gene from an individual of Sardinian descent who is a compound heterozygote for the beta zero-thalassemia codon 39 (C-->T) nonsense mutation and the Sardinian delta beta-thalassemia [codon 39(C-->T)/-196(C-->T)A gamma]. The analysis of the delta-globin gene from the delta beta-thalassemia chromosome revealed an entirely normal sequence. The defective function of the delta-globin gene in this determinant is thus likely related to a suppressive effect of the in cis nondeletional high persistence of fetal hemoglobin mutation of the A gamma gene, probably resulting from an increased capability of the relative promoter to interact with the locus control region.

Base Sequence↗
PubMed1991

Hemoglobin Cagliari (beta 60 [E4] Val----Glu): a novel unstable thalassemic hemoglobinopathy.

This report describes a patient with thalassemia intermedia-like phenotype born to normal parents in whom globin gene sequencing detected a novel abnormal hemoglobin (Hb) due to a T to A substitution at codon 60 of the beta-globin gene arising as a de novo mutation. Normal sequences were detected at the homologous beta-globin locus. This mutation results in the substitution of a polar (glutamic acid) for a nonpolar (valine) residue near the corner of the heme pocket of the beta-globin chain. The novel variant has been designated Hb Cagliari, from the place of birth of the propositus. Kinetics of globin synthesis performed following splenectomy suggest that this new Hb variant is synthesized at a near normal rate but undergoes rapid breakdown. The extreme lability of the variant explains the clinical and hematologic picture characterized by marked ineffective erythropoiesis, thalassemia-like bone changes, iron overload, high proportion of Hb F in the peripheral blood, reduced beta/alpha-globin chain synthesis ratio in peripheral blood reticulocytes, and absence of the abnormal Hb in peripheral blood at extensive protein structural analysis before splenectomy. This case indicates that a thalassemic hemoglobinopathy should be suspected in the presence of a patient with a thalassemia intermedia-like phenotype born to normal parents, even when protein structural analysis fails to detect an abnormal Hb. DNA sequencing may allow to define the mutation, thus making the proper diagnosis.

Anemia, Hemolytic↗
PubMed1991

Clinical utility of fractionating erythrocytes into "Percoll" density gradients.

Two rapid methods for fractionating the RBC into five or nine layers of increasing density are reported. These procedures have been used to monitor the decline of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) activity during the process of red cell aging in normal subjects and in beta-thal carriers, to study transfused patients with G6PD and pyruvate kinase (PK) deficiency and to test the effects of inositol hexaphosphate (IHP) encapsulation on RBC subpopulations.

Adult↗
PubMed1991

Percentile curves for red cell indices of beta zero-thalassaemia heterozygotes in infancy and childhood.

This paper describes the percentile curves for red blood cell (RBC) count, Hb, mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values of beta zero-thalassaemia heterozygotes during infancy, childhood and adolescence. Hb values were about 2 g/dl below those of normal controls with a progressive increase with age paralleling the normal developmental trend. The Hb increase with age was due to a progressive rise in the Hb content per cell, the number of RBC remaining nearly constant. MCV and MCH values also increased with age with a pattern parallel to normal control. Because of the high prevalence of alpha-thalassaemia in the Sardinian population, to which all the subjects investigated belong, the 3rd MCH-MCV percentile curves of normal overlap the 97th curve of beta-thalassaemia heterozygotes. The HbA2 levels, however, were always increased as compared to normal. These results confirm in children than screening for heterozygous beta-thalassaemia in populations with a high incidence of alpha and beta-thalassaemia by MCV-MCH determination may overlook a sizeable proportion of beta-thalassaemia carriers. The knowledge of the extent of variation of RBC indices of beta-thalassaemia heterozygotes during infancy, childhood and adolescence, is very useful for the evaluation of a child presenting with a mild microcytic anaemia.

Adolescent↗
PubMed1991

Population-based genetic screening.

A preventive genetic programme aimed to control beta-thalassemia in the Sardinian population is based on a combination of increased awareness of the population, carrier screening, genetic counselling and prenatal diagnosis. As a result, the registry of thalassemia major demonstrated a profound decline in the incidence of this disease from 1 per 250 to 1 per 1200 live births, with 90% of cases effectively prevented.

Adult↗
PubMed1991

Thalassemias in Sardinia: molecular pathology, phenotype-genotype correlation, and prevention.

This article reviews the molecular bases of alpha- and beta-thalassemias in Sardinia. In addition, it describes the characteristics and the effects of a genetic program designed to prevent homozygous beta-thalassemia. In the large majority of the cases (95.7%), beta-thalassemia is caused by the nonsense mutation at codon 39, followed by frameshifts at codon 6 (2.1%). Homozygous beta-thalassemia most commonly results in thalassemia major, but in a small proportion this genotype produces milder forms referred to as thalassemia intermedia. The reasons for the attenuated forms were determined only in a small proportion of the cases. The reduced clinical severity was due to either of two factors: (a) There could be the presence of cytosine-thymidine (C----T) substitution of position - 158 G gamma, which is able to increase the G gamma chain output (as in homozygotes for frameshift at codon 6 or compound heterozygote for frameshift at codon 6 and codon 39 nonsense mutation). (b) Reduced clinical severity could be the result of co-inheritance of alpha-thalassemia in the form of two alpha-globin gene deletions of functional loss of the alpha 2-globin gene (homozygote for codon 39 nonsense mutation). The most prominent clinical form of alpha-thalassemia is hemoglobin H disease, which may result from the compound heterozygous state for deletion alpha 0- and alpha(+)-thalassemia (in 83.1% of cases) or deletion and nondeletion alpha-thalassemia (in 16.9%). Deletion Hb disease shows a milder clinical picture as compared to the nondeletion form. The most common nondeletion alpha-thalassemia is the ATG----ACG substitution at the initiation codon of the alpha 2 gene. Double heterozygotes of alpha (-alpha/-alpha) and beta-thalassemia or delta- and beta-thalassemia are relatively common and may cause confusion in carrier identification. The preventive program aimed to control beta-thalassemia is based on voluntary carrier screening., counselling, and prenatal diagnosis. Prenatal diagnosis is carried out by dot blot analysis with allelic specific oligonucleotides on amplified trophoblast DNA. This procedure gave very reliable results; in fact, no misdiagnosis has occurred so far. The preventive program was highly effective, resulting in a decline of the incidence of thalassemia major from 1:250 to 1:1,000 live births.

Base Sequence↗
PubMed1990

Fetal hydrops in Sardinia: implications for genetic counselling.

This paper describes the first case of Hb Bart's hydrops fetalis syndrome in the Sardinian population. Despite the high frequency of a-thalassemia, fetal hydrops is extraordinarily rare in the Sardinian population because a-thalassemia is more usually the result of the single a-thalassemia globin gene deletion and is very rarely produced by the deletion of two a-globin genes. The fetus, the product of a consanguineous marriage at risk for beta-thalassemia, was monitored by chorionic villi DNA analysis which detected the heterozygous state for the codon 39 nonsense mutation. Follow-up ultrasound examination showed fetal hydrops, which led us to carry out further investigation. Hemoglobin and a-globin gene analysis on cord blood obtained by cordocentesis revealed the homozygous state for the most common deletion ao-thalassemia in Mediterranean populations. Retrospective evaluation of the father's hematological features showed very low MCH-MCV for a beta-thalassemia carrier which may indicate co-inherited a-thalassemia. These findings indicate that careful evaluation of red cell indices of parents at risk for beta-thalassemia and adequate consideration of the consanguinity may point to co-inherited a-thalassemia and lead to the appropriate analysis.

Chorionic Villi Sampling↗
PubMed1990

Antenatal diagnosis of beta-thalassemia in Sardinia.

This paper reviews the characteristics and the results of 15 years of experience with a preventive program, based on carrier screening and prenatal diagnosis, designed to control thalassemia major in the Sardinian population. The education of the population about thalassemia and the modalities for its prevention was accomplished via the mass media. Carrier screening was carried out voluntarily on couples of child-bearing age. Prenatal diagnosis was initially carried out by fetal blood analysis; since 1983, it has been done by DNA analysis on non-amplified or amplified DNA. Different chorionic villous sampling procedures have been used. Nowadays, we have adopted the transabdominal approach because, in our experience, it seems to be associated with a low risk (2%) of fetal mortality. At the present time, the beta-thalassemia mutations are detected directly by dot-blot analysis of amplified DNA with 32P- or horseradish peroxidase-labeled allele-specific oligonucleotide probes. Two oligonucleotide probes, one complementary to the codon-39 nonsense mutation, which accounts for 95.7% of the beta-thalassemia chromosomes in the Sardinian population, and the other complementary to the frameshift at codon 6, which is the second most common mutation in our population (2.1%), allow us to make prenatal diagnosis in the large majority of cases. Notwithstanding a careful dissection of maternal decidua from chorionic villi, co-amplification of maternal sequence was detected in 4 out of 425 cases tested by this procedure. In order to avoid this pitfall, the simultaneous amplification of highly polymorphic VNTR (variable number of tandem repeats) segments could be used. On the whole we have so far carried out 2711 prenatal tests: 1130 by fetal blood analysis, 1156 by oligonucleotide hybridization on electrophoretically separated DNA fragments, and 425 by dot-blot analysis on amplified DNA with allele-specific oligonucleotide probes. Two errors occurred by fetal blood analysis and none by DNA analysis. The incidence of thalassemia major declined from 1:250 live births in the absence of prevention to 1:1000 after the establishment of this program, indicating that carrier screening and prenatal diagnosis are effective means for preventing thalassemia major at the population level.

Female↗
PubMed1989

Molecular analysis of beta zero-thalassemia intermedia in Sardinia.

In this study we have carried out alpha- and beta-globin gene analysis and defined the beta-globin gene polymorphisms in a group of patients with thalassemia intermedia of Sardinian descent. A group of patients (109) with thalassemia major of the same origin served as control. Characterization of the beta-thalassemia mutation showed either a frameshift mutation at codon 6 or a codon 39 nonsense mutation. We found that homozygotes for the frameshift mutation at codon 6 or compound heterozygotes for this mutation and for the codon 39 nonsense mutation develop thalassemia intermedia more frequently than thalassemia major. The frameshift mutation at codon 6 was associated with haplotype IX that contains the C-T change at position -158 5' to the G gamma globin gene implicated in high gamma chain production and thus the mild phenotype. In patients' homozygotes for codon 39 nonsense mutation, those with thalassemia intermedia more frequently had the two-gene deletion form of alpha-thalassemia, or functional loss of the alpha 2 gene as compared with those with thalassemia major. In a few siblings with thalassemia major and intermedia, the thalassemia intermedia syndrome correlated with the presence of the -alpha/-alpha genotype. No cause for the mild phenotype was detected in the majority of patients who had not inherited either haplotype IX or alpha-thalassemia.

Blotting, Southern↗
PubMed1989

Erythropoiesis following bone marrow transplantation from donors heterozygous for beta-thalassaemia.

This study shows a marked and protracted activation of HbF synthesis in homozygous beta.-thalassaemia patients transplanted from HLA identical siblings heterozygous for beta-thalassaemia, as compared to patients transplanted from normal donors. HbF synthesis in recipients was much higher in relation to the corresponding bone marrow donor values either normal or heterozygous for beta thalassaemia. gamma-chain synthesis and G gamma/A gamma ratio were also studied in peripheral blood BFU-E from recipients and their donors. BFU-E from donors heterozygous for beta-thalassaemia showed higher gamma chain synthesis as compared to normal donors. Peripheral blood BFU-E gamma/beta + gamma ratios and G gamma percentage were higher in recipients than in their corresponding donors both normal or heterozygotes. The marked and protracted reactivation of HbF synthesis in recipients of heterozygous beta-thalassaemia bone marrow most likely results from an increased erythropoietic stress on erythroid progenitors. In order to obtain adequate Hb levels heterozygous beta-thalassaemia bone marrow should produce more red blood cells to compensate for the low MCH. The magnitude of activation of HbF synthesis was very variable. This variability may result from inherited differences in the capacity of reactivation of HbF synthesis of red cell progenitors from heterozygous beta-thalassaemia under stressed erythropoiesis.

Blood Donors↗
PubMed1989

Interaction between deletion delta-thalassemia and beta zero-thalassemia (codon 39 nonsense mutation) in a Sardinian family.

This paper describes individuals of Sardinian descent with heterozygous normal-Hb A2 beta-thalassemia who have a chromosome with a 7.2 Kb deletion in the psi beta/delta globin intergenic region and a chromosome with the codon 39 nonsense mutation. The propositus has the typical thalassemia-like red cell indices with a relatively high Hb level (13.4 g/dl) for a beta-thalassemia carrier, indicating a normal function of the beta-globin gene in cis to the 7.2 Kb deletion. The deletion starts between the psi beta and delta genes and ends in the IVS-2 of the delta-gene. His breakpoints are identical to a previously described deletion detected in the homozygous state in a patient with thalassemia intermedia, homozygous for G-greater than A mutation at position 5 of IVS-1. Because the mutation herein described silences the delta-globin gene and leaves intact the function of the in cis beta-globin gene we propose the definition of deletion delta zero-thalassemia.

Chromosome Deletion↗
PubMed1989

The prevention of thalassemia in Sardinia.

In this paper we review the characteristics and effectiveness of a program aimed at preventing homozygous beta-thalassemia in the Sardinian population. The target population for screening were couples at marriage, conception or early pregnancy. Awareness of the problem and the involvement of the population were achieved via the mass media or by personal approaches through lectures or discussions. Parents' Associations were consulted and have made themselves available to prospective couples in several critical areas. Education on thalassemias was introduced into the school curriculum. Counseling was based on private interviews at which the several options available were discussed with the individual carrier or the couples. Prenatal diagnosis was chosen by the large majority of couples counseled. The introduction of 1st trimester diagnosis resulted in a striking increase of the acceptance rate from 93.2 to 99.1%. Prenatal diagnosis was carried out initially by fetal blood analysis and thereafter by trophoblast or amniocyte DNA analysis. Direct detection of the mutation by oligonucleotide hybridization on agarose gel separated DNA fragments or by dot-blot analysis with allelic specific oligonucleotide probes on enzymatically amplified DNA was used. This program resulted in a decline in thalassemia major births of 90%. The reasons for residual cases were mostly lack of information and, less frequently, misdiagnoses or refusal of fetal diagnosis.

Adult↗
PubMed1988

Interaction of heterozygous beta zero-thalassemia with single functional alpha-globin gene.

In this study, we analyzed the phenotypic manifestations resulting from the interaction of heterozygous beta zero-thalassemia(beta zero-39 nonsense mutation) with the functional loss of three alpha-globin structural genes in six subjects, of whom four had the [-alpha/--]alpha-globin genotype and two the [--/alpha Th alpha] alpha-globin genotype. The beta-thalassemia defect was in all cases the nonsense mutation at codon 39. The nondeletion alpha-thalassemia alpha th was the initiation codon mutation (AUG----GUG) of the alpha-2 gene. In all these subjects hypochromia and microcytosis were more marked than in beta zero-thalassemia heterozygotes with a full complement of four alpha-globin genes. All but one had moderate anemia. The alpha:beta globin chain synthesis ratios were consistently decreased. No cases had Hb H on electrophoresis. Subjects with [--/alpha Th alpha] alpha-globin genotype had more severe thalassemia-like manifestations than those with [--/-alpha] alpha-globin genotype.

Adolescent↗
PubMed1988

Pitfalls in genetic counselling for beta-thalassemia: an individual with 4 different thalassemia mutations.

This paper describes a complex combination of four thalassemia genes (delta(+), beta(0), nondeletion and deletion alpha-thalassemia) in the spouse of a typical high Hb A2 beta-thalassemia carrier presenting for genetic counselling. This complex gene combination resulted in a hematological phenotype, characterized by thalassemia-like red cell indices, normal Hb A2 and Hb F levels and slightly reduced alpha/beta globin chain synthesis ratio, and therefore not indicative for the presence of beta-thalassemia trait. Family studies in combination with alpha-globin gene mapping, haplotype analysis at the beta-globin gene cluster and definition of the beta-thalassemia mutation by oligonucleotide hybridization led us to identify a beta-thalassemia mutation, to define the molecular basis for this phenotype and give the appropriate genetic counselling.

Female↗
PubMed1988

Mechanism of Hb F stimulation by S-stage compounds. In vitro studies with bone marrow cells exposed to 5-azacytidine, Ara-C, or hydroxyurea.

The in vitro effect of S-stage-specific drugs on the fetal hemoglobin (Hb F) potential of erythroid precursors and progenitors was tested by exposing bone marrow cells to 5-aza-2'-deoxycytidine, Ara-C, or hydroxyurea in suspension cultures and reculturing the cells in drug-free clonal cultures. Analysis of Hb F in the erythroblasts present at the end of suspension cultures and in the erythroid colonies formed from treated progenitors showed that 1 X 10(-9)-5 X 10(-8) M 5-aza-2'-deoxycytidine produced a concentration-related increase in the proportion of Hb F-positive erythroblasts, of Hb F-positive erythroid CFU (CFUe) colonies, and at the higher doses used, an increased Hb F expression in erythroid burst-forming unit (BFUe)-derived colonies. Preincubation of bone marrow cells with Ara-C produced significant megaloblastic changes by the end of the 2-d incubation and increased the proportion of Hb F-positive erythroblasts, CFUe colonies, and e-clusters, but BFUe-derived progeny was unaffected. Hydroxyurea failed to produce significant changes in Hb F at the range of concentrations used. The data raise the possibility of more than one mechanism underlying the stimulation of Hb F by S-stage drugs.

Azacitidine↗
PubMed1988

Delineation of the molecular basis of delta- and normal HbA2 beta-thalassemia.

In this study, we used cloning and sequence analysis to define the molecular defect in two delta-thalassemia genes, one associated with reduced output of delta-globin chains (delta +thal) from a Sardinian and the other with a complete suppression of delta-chain production from the affected locus (delta zerp thal) from a Southern Italian. Sequence analysis of the delta +thal gene showed a G----T substitution at the first nucleotide of codon 27 (delta +27) which produces an amino acid change (Ala----Ser) and presumably activates a cryptic splice site located at this position. Therefore, only a fraction of the transcript is processed from this site, as indicated by the clinical phenotype of delta +thal. DNA sequencing of the delta zero thal gene revealed a T----C substitution at position 1 of IVS-1, which abolishes the splicing at this site and thus leads to complete deficiency of normal mRNA explaining the clinical phenotype of delta zero thal. Oligonucleotide analysis was used to confirm the coinheritance of the delta +27 mutation in a group of Sardinians with thalassemia like phenotype and normal HbA2 level who, on the basis of genetic criteria, were supposed to be double heterozygous for delta-thalassemia and beta-thalassemia. The definition of delta-thalassemia defects in each high-risk area facilitates identification of double heterozygotes for delta- and beta-thalassemia by DNA analysis and may thus improve genetic counseling.

Base Sequence↗