Laboratory diagnosis for thalassemia intermedia: Are we there yet?

BACKGROUND

Differentiation between thalassemia major and thalassemia intermedia at presentation is not uniformly characterized, for which an absolute criteria needs to be developed. This study investigated the primary and secondary genetic modifiers to develop a laboratory finding by forming different genetic mutational combinations seen among thalassemia intermedia patients and comparing them with thalassemia major.

METHODS

This cross-sectional study analyzed 315 thalassemia intermedia patients. One hundred and five thalassemia major patients were recruited on the basis of documented evidence of diagnosis and were receiving blood transfusion therapy regularly. Various mutational combinations were identified, and comparison was performed between thalassemia intermedia and major using statistical software STATA 11.1.

RESULTS

The mean age of the total population was 5.9 ± 5.32 years of which 165 (52%) were males. Of the two groups (thalassemia intermedia and thalassemia major), IVSI-5, IVSI-1, and Fr 8-9 were more prevalent among the thalassemia intermedia cohort. When comparison was performed between the thalassemia intermedia and thalassemia major patients, it showed significant results for the presence of Xmn-1 polymorphism.

CONCLUSION

The presence of IVSI-5 homozygous with Xmn-1, IVSI-5 heterozygous with Xmn-1, Cd 30 homozygous with or without Xmn-1 and IVSI-1 homozygous or heterozygous either with or without Xmn-1 prove to be strong indicators towards diagnosis of thalassemia intermedia.

New therapeutic targets in transfusion-dependent and -independent thalassemia

β-Thalassemias are characterized by reduced production of β-globin chain, resulting in α/β-chain unbalance and precipitation of α-globin-heme complexes and determining ineffective erythropoiesis. Ineffective erythropoiesis, chronic hemolytic anemia, and compensatory hematopoietic expansion are the disease hallmarks, and they are related to the severity of the chain unbalance. Several clinical forms of β-thalassemia, including the coinheritance of β-thalassemia with hemoglobin E resulting in hemoglobin E/β-thalassemia, have been described. Clinically, β-thalassemias can be classified as transfusion-dependent thalassemia (TDT) and non-transfusion-dependent thalassemia (NTDT) according to the severity of the phenotype, which is caused by a wide spectrum of mutations in a homozygous or compound heterozygous state. Current treatment of TDT consists of regular transfusions that lead to iron overload, requiring iron chelation to prevent iron-related organ toxicity. NTDT patients do not require transfusions or only occasionally require them; however, they develop iron overload as well because of increased intestinal iron absorption caused by chronic anemia. Hematopoietic stem cell allogenic transplant is the only approved cure for β-thalassemia; however, it is still limited by clinical conditions and the availability of matched donors as well as by potential graft-versus-host disease (GVHD). Gene therapy could avoid the GVHD risk, although hematopoietic stem cells must be genetically modified ex vivo. Epigenetic manipulation and genomic editing are novel experimental approaches. An increased understanding of the pathophysiology that controls the disease process prompted us to explore alternative therapeutic approaches that address the underlying chain unbalance, ineffective erythropoiesis, and iron dysregulation. Molecules, such as JAK2 inhibitors and the activin-receptor ligand trap that target ineffective erythropoiesis, are already in clinical trials with promising results. Other agents aimed to generate iron-restricted erythropoiesis are also under experimental evaluation.

Kidney Function in Patients With Different Variants of Beta-Thalassemia

INTRODUCTION

Renal involvement is a rare complication of β-thalassemia. Both tubular and glomerular dysfunction might occur in these patients. The aim of this study was to evaluate and compare kidney function in the major, intermedia, and minor variants of β-thalassemia.

MATERIALS AND METHODS

Renal tubular and glomerular function of 72 patients with β-thalassemia (25 major, 23 intermedia, and 24 minor) were evaluated. Patients older than 40 years and those with chronic kidney disease, diabetes mellitus, congestive heart failure, associated infections, congenital anomalies of the kidney and urinary tract were excluded. Blood and urine samples were collected electrolytes and markers of kidney function.

RESULTS

Mean age at the time of study was significantly higher in the minor group. The majority of patients with thalassemia major were males. Hematuria and pyuria occurred in 4% to 8% of the patients. Serum level of all variables were within normal limits, with no significant difference between the three groups. Glomerular filtration rate was nonsignificantly higher in the major and intermedia groups, compared to the minor variant. A significantly lower urine phosphorus and uric acid excretion was noted with the minor variant. Urine phosphorus and uric acid excretion increased more frequently in the major and intermedia groups.

CONCLUSIONS

Tubular and glomerular functions appear to be well preserved in all variants of β-thalassemia.

Frataxin expression in reticulocytes of non-splenectomized and splenectomized patients with HbE-β-thalassaemia

OBJECTIVES

A previous report revealed that thalassaemic patients with transfusional iron overload developed oxidative stress. The aims of this study were to investigate the FXN mRNA levels in the reticulocytes of patients with HbE-beta-thalassaemia who were treated with regular transfusions, to compare the results with those from normal controls and to evaluate the relationships of the levels of FXN mRNA with malondialdehyde (MDA) and iron parameters in these patients.

DESIGN AND METHODS

The levels of FXN mRNA in the reticulocytes of patients (30 non-splenectomized and 30 splenectomized) and 30 normal individuals were assessed by RT-PCR. The levels of MDA and the transferrin saturations (TSs) were analysed with thiobarbituric acid-reactive substance assay and spectrometry, respectively. The level of ferritin was determined by ELISA.

RESULTS

The levels of FXN mRNA, MDA, ferritin, and TS in the patients were significantly higher than those in the controls. The levels of FXN mRNA, MDA, and ferritin in the non-splenectomized and splenectomized patients were significantly different, but the levels of TS in these two patient groups were comparable. The relative FXN expression in the patients was found to be correlated with the levels of MDA and ferritin but not correlated with TS.

CONCLUSIONS

The elevation of FXN expression in the reticulocytes of these patients seems to be linked to oxidative stress and iron status.

Homozygous deletion of six olfactory receptor genes in a subset of individuals with Beta-thalassemia

Progress in the functional studies of human olfactory receptors has been largely hampered by the lack of a reliable experimental model system. Although transgenic approaches in mice could characterize the function of individual olfactory receptors, the presence of over 300 functional genes in the human genome becomes a daunting task. Thus, the characterization of individuals with a genetic susceptibility to altered olfaction coupled with the absence of particular olfactory receptor genes will allow phenotype/genotype correlations and vindicate the function of specific olfactory receptors with their cognate ligands. We characterized a 118 kb β-globin deletion and found that its 3′ end breakpoint extends to the neighboring olfactory receptor region downstream of the β-globin gene cluster. This deletion encompasses six contiguous olfactory receptor genes (OR51V1, OR52Z1, OR51A1P, OR52A1, OR52A5, and OR52A4) all of which are expressed in the brain. Topology analysis of the encoded proteins from these olfactory receptor genes revealed that OR52Z1, OR52A1, OR52A5, and OR52A4 are predicted to be functional receptors as they display integral characteristics of G-proteins coupled receptors. Individuals homozygous for the 118 kb β-globin deletion are afflicted with β-thalassemia due to a homozygous deletion of the β-globin gene and have no alleles for the above mentioned olfactory receptors genes. This is the first example of a homozygous deletion of olfactory receptor genes in human. Although altered olfaction remains to be ascertained in these individuals, such a study can be carried out in β-thalassemia patients from Malaysia, Indonesia and the Philippines where this mutation is common. Furthermore, OR52A1 contains a γ-globin enhancer, which was previously shown to confer continuous expression of the fetal γ-globin genes. Thus, the hypothesis that β-thalassemia individuals, who are homozygous for the 118 kb deletion, may also have an exacerbation of their anemia due to the deletion of two copies of the γ-globin enhancer element is worthy of consideration.

Comparative evaluation of renal findings in Beta-thalassemia major and intermedia

Thalassemia is a systematic disease in which the renal involvement has not yet been scrupulously studied. In a cross-sectional study, the renal findings of 50 cases of thalassemia intermedia (group 1) were compared to 58 patients with thalassemia major (group 2). Blood urea nitrogen, serum creatinine, uric acid, calcium, phosphorus, urinalysis, and ultrasonographical findings were evaluated. Mean age was 18 +/- 3.0 in group 1 and 17 +/- 3.5 years in group 2. The mean of serum ferritin levels was 871 +/- 81.8 ng/ml in group 1 vs. 3503 +/- 201 ng/ml in thalassemia major (p > 5) was observed among 19 children (17.6%); 17 of them were in group 1. In contrast, children with thalassemia major had significantly higher serum creatinine (0.89 +/- 0.18 vs. 0.59 +/- 0.37 mg/dl, p < 0.05) and blood urea nitrogen values (12.14 +/- 5.58 vs. 13.85 +/- 3.54 mg/dl, p < 0.05). We conclude that significant renal involvement is not a frequent complication in children and young adults suffering from thalassemia. Hyperuricemia and microscopic hematuria are more common in thalassemia intermedia than thalassemia major. Microscopic hematuria in thalassemia intermedia might be related to either hypercalciuria or hyperuricosuria.

Cerebrovascular accident in beta-thalassemia major (beta-TM) and beta-thalassemia intermedia (beta-TI)

Chronic hypercoagulable state expressed clinically by thromboembolic events has been described in thalassemia. One of the affected organs is the brain where symptomatic and asymptomatic damage has been reported. The present report describes seven cases who presented with the signs of cerebrovascular accident (CVA), five ischemic and two with hemorrhage. Two of them died. All patients were splenectomized, five received regular blood transfusions, and their ferritin levels were between 1,200 and 3,000 mg %. In addition, four patients had congestive heart failure and atrial fibrillation, and three had "Bronze diabetes," The recommendation on the basis of the results is that well-designed clinical trials are indicated to monitor asymptomatic brain damage by magnetic resonance imaging in splenectomized patients over the age of 20 years, who are not regularly transfused and have a high risk to develop thromboembolic events. In this subset of patients, anticoagulant and/or antiplatelet therapy should be considered. Moreover, treatment of additional complications resulting from iron overload, which may contribute to the etiology of CVA such as cardiac failure and arrhythmia with or without "bronze diabetes," is mandatory.

Severe beta(0) thalassemia/hemoglobin E disease caused by de novo 22-base pair duplication in the paternal allele of beta globin gene

beta Thalassemia is a major public health concern in Southeast Asia. A prevention program has been implemented in Thailand comprising mass carrier screening and genetic testing. In this study, a Thai girl with severe beta thalassemia/hemoglobin (Hb) E disease was born from the mother with Hb E trait and the genotypically normal father. DNA sequencing revealed novel 22-bp tandem duplication in the paternal allele of beta globin gene, producing a severely truncated product. A short recurring nucleotide at the insertion site suggested a predisposition to this mutation. Therefore, spontaneous beta globin mutations occasionally occur in normal population. Its clinical significance is noteworthy in countries with high prevalence of beta thalassemia.

A new stratification strategy that identifies a subset of class III patients with an adverse prognosis among children with beta thalassemia major undergoing a matched related allogeneic stem cell transplantation

One hundred ninety patients underwent 197 HLA-matched related allogeneic stem cell transplantation for a diagnosis of beta thalassemia major at our center. The median age (+/-SD) was 7+/-4.1 years, and there were 129 (68%) males. Age and liver size as continuous variables were significantly associated with an adverse outcome. Using a receiver operator characteristics curve plot analysis, cutoff values of 7 years and 5 cm for age and liver size, respectively, were associated with the highest likelihood ratio of an adverse impact. On a multivariate analysis age>or=7 years and liver size>or=5 cm had a significant impact on event free survival (EFS) (relative risk 2.2 and 2.7, P values .014 and .000, respectively). Using these 2 variables, patients were categorized as high risk if they were >or=7 years and had a liver size>or=5 cm (n=41; all belonged to Class III). The 5-year EFS and overall survival (OS) in this high-risk group was 23.93+/-6.88 and 39.01+/-7.96, whereas in the remaining Class III patients (n=64) it was 70.3+/-6.06 and 78.3+/-5.5, respectively. This risk stratification identifies a significant subset (39%) of patients among those in Class III who have a poor outcome with a conventional myeloablative allogeneic stem cell transplantation. Patients in this high-risk group would probably benefit from novel therapeutic approaches.

Quality of Life in Patients with Thalassemia Intermedia Compared to Thalassemia Major

The impact of thalassemia major and thalassemia intermedia and their associated complications on quality of life (QOL) is largely unknown. Determining the degree of health impairment as perceived by the patient is essential information needed to recommend suitable therapy. The objective of this study was to evaluate QOL in transfusion-independent patients with thalassemia (non-Tx) compared with that in transfused patients (Tx) and to identify the factors that affect QOL in thalassemia. A convenient sample of 48 thalassemia patients (29 Tx and 19 non-Tx) with mean age of 14.6 years (SD = 7.5 years) were selected during a comprehensive visit to complete a Dartmouth Primary Care Cooperative Information Chart System (COOP) questionnaire. Patients rated QOL from excellent (1) to poor (5) on five dimensions of health status. Scores of 4 or 5 represent major limitations. These results were augmented by a brief medical history and chart review. Forty-one percent of Tx patients and 47% of non-Tx patients reported severe impairments in 1-6 and 1-2 domains, respectively. The most commonly reported affected domains were feelings such as anxiety, depression, and concern of overall health status or indications of recent deterioration in health. In contrast with previous beliefs, transfusion-independent thalassemia patients also suffer serious impairment in QOL. Presented data suggest that all patients with thalassemia undergo QOL assessment so that interventions focused on affected domains can be implemented.

A novel molecular basis for β thalassemia intermedia poses new questions about its pathophysiology

During a study of the molecular basis for severe forms of β thalassemia in Sri Lanka, 2 patients were found to be heterozygous for β thalassemia mutations. Further analysis revealed that one of them has a previously unreported molecular basis for severe thalassemia intermedia, homozygosity for quadruplicated α globin genes in combination with heterozygous β thalassemia. The other is homozygous for a triplicated α globin gene arrangement and heterozygous for β thalassemia. Their differences in clinical phenotype are explainable by the interaction of other genetic factors and, in particular, their early management. The clinical course of the 2 propositi underlines the importance of full genotyping and a long period of observation before treatment is instituted, particularly in patients with β thalassemia intermedia associated with extended α globin gene arrangements. The hemoglobin (Hb) F levels in these patients with severe β thalassemia intermedia, compared with other forms of this condition in the Sri Lankan population and elsewhere, are unusually low, a consistent finding in extended α globin gene interactions and in dominant β thalassemia, raising the possibility that increased levels of HbF production in β thalassemia may require mutations at both β globin gene loci.

Hemoglobin E-β-Thalassemia: Progress Report from the International Study Group

A long-term observational study of Hb E-beta-thalassemia in Sri Lanka is beginning to define some of the genetic and environmental factors that are responsible for its remarkable phenotypic variability. In this population there is a very small difference between the steady-state hemoglobin levels between the mild and severe phenotypes, and it has been possible to stop transfusion in many of those who have been on long-term treatment of this kind. These preliminary observations, made over the last 7 years, provide directions for future research into this increasingly important disease.

Genetic modifiers of beta-thalassemia

As the defective genes for more and more genetic disorders become unravelled, it is clear that patients with apparently identical genotypes can have many different clinical conditions even in simple monogenic disorders. Beta thalassemia occurs when there is a deficiency in the synthesis of beta globin chains. The clinical manifestations of beta thalassemia are extremely diverse, spanning a broad spectrum from severe anemia and transfusion-dependency to the asymptomatic state of thalassemia trait. The remarkable phenotypic diversity of the beta thalassemias is prototypical of how a wide spectrum of disease severity can be generated in single gene disorders. The most reliable and predictive factor of disease phenotype is the nature of the mutation at the beta globin locus itself. However, relating phenotype to genotype is complicated by the complex interaction of the environment and other genetic factors at the secondary and tertiary levels, some implicated from family studies, and others, as yet unidentified. This article reviews the clinical and hematologic diversity encountered in beta thalassemia with an overview of the modifier genes that moderate their disease expression.

Heterogeneity of the egammadeltabeta-thalassaemias: characterization of three novel English deletions

We have characterized three novel epsilon gamma delta beta-thalassaemia deletions in three English families. Two of the deletions, 114 and 439 kb, removed the entire beta-globin gene complex, including a variable number of flanking olfactory receptor (HOR) genes. The 98-kb deletion extended 90-kb upstream of the epsilon gene to 8 kb upstream of the G gamma-gene, leaving the gamma,delta and beta-genes intact. The 439 kb deletion is the largest deletion reported so far to cause epsilon gamma delta beta-thalassaemia; heterozygotes for this deletion were variably affected by neonatal haemolytic anaemia. Two of the deletions were de novo. Breakpoints of all three deletions occurred within regions of L1 or Alu repeats and contained short regions of direct homology between the flanking sequences, a feature that is likely to have contributed to the illegitimate recombinations.

[Quantitative analysis of human globin gene expression in beta-thalassemia using real-time RT-PCR]

Whole blood samples were collected from 100 normal healthy adults, from umbilical cord of 33 newborn infants, 111 individuals with beta-thalassemia minor (beta(T)/beta(A),alphaalpha/alphaalpha) and 39 with beta-thalassemia major (beta(T)/beta(T),alphaalpha/alphaalpha). Prior to quantitative analysis of globin gene expression, DNA was extracted from all blood samples and used for beta-thalassemia genotype analysis. Different types of beta globin gene mutations were analyzed using reverse dot blotting (RDB) method. Total RNA were extracted and subjected to real-time RT-PCR for quantitative measurement of alpha, beta and gamma globin mRNA using three sets of primers and fluorescent-labeled probes, designed according to the sequences of alpha, beta and gamma human globin gene. Real-time RT-PCR was performed in ABI 7700 system. Following the real-time RT-PCR, the mean values of alpha, beta and gamma globin mRNA were calculated and the ratios of alpha/beta, alpha/(beta + gamma ) and gamma /(beta + gamma ) were determined to characterize the relative expression levels of different globin genes among normal adult, infant, beta-thalassemia minor and beta-thalassemia major patients. The resultant data were analyzed using SPSS 10.0 software to determine statistical significance of human globin gene expression among normal controls and beta-thalassemia patients. Due to vast variations of the mean globin gene mRNA levels among different groups, log conversion of alpha/beta + 1, alpha/(beta + gamma ) + 1 and gamma /(beta + gamma ) +1 was used for statistical analyses and intergroup comparison. The alpha/beta globin gene mRNA ratios were determined to be 4.62+/-1.20, 7.81+/-2.89, 13.51+/-5.12, and 188.24+/-374.04 for normal healthy adult (beta(A)/beta(A),alphaalpha/alphaalpha), infant (beta(A)/beta(A),alphaalpha/alphaalpha), beta- thalassemia minor (beta(T)/beta(A),alphaalpha/alphaalpha) and beta-thalassemia major(beta(T)/beta(T),alphaalpha/alphaalpha) respectively. The alpha/(beta+ gamma ) ratios were 4.43+/-1.17, 0.56+/-0.49, 9.62+/-4.37, and 2.14+/-1.58 for normal healthy adult (beta(A)/beta(A),alphaalpha/alphaalpha), infant (beta(A)/beta(A),alphaalpha/alphaalpha), beta- thalassemia minor (beta(T)/beta(A),alphaalpha/alphaalpha) and beta- thalassemia major(beta(T)/beta(T),alphaalpha/alphaalpha) respectively. The gamma /(beta+ gamma ) ratios were 0.04+/-0.03, 0.92+/-0.06, 0.28+/-0.18, and 0.95+/-0.04 for normal healthy adult (beta(A)/beta(A),alphaalpha/alphaalpha), infant (beta(A)/beta(A),alphaalpha/alphaalpha), beta- thalassemia minor (beta(T)/beta(A),alphaalpha/alphaalpha) and beta- thalassemia major (beta(T)/beta(T),alphaalpha/alphaalpha) respectively. Following statistical analyses, the alpha/beta and alpha/(beta+ gamma ) globin gene mRNA ratios were significantly different among four different groups (normal adult, normal infant, beta- thalassemia minor and beta- thalassemia major). The gamma /(beta + gamma ) globin gene mRNA ratio was significantly different among all groups except for between infant and beta- thalassemia major patients. Human beta globin gene mRNA levels decrease progressively and dramatically from normal adults to beta-thalassemia patients with beta-thalassemia major having the lowest levels. On the other hand, the gamma globin gene mRNA levels increase progressively from normal adult to beta-thalassemia patients with beta-thalassemia major having the highest levels. Infants have relatively lower levels of beta but higher levels of gamma globin gene mRNA as compared to those in normal adults. Thus, the relative expression levels of alpha, beta or gamma globin genes varied but inter-related among different ages of normal individuals and different beta-thalassemia genotypes.

Attenuation of oxidative stress-induced changes in thalassemic erythrocytes by vitamin E

The oxidative stress status of the transfusion-dependent Ebeta- and beta-thalassemia patients were studied before and after treatment with vitamin E for a period of four weeks. The level of cellular vitamin antioxidants viz. ascorbic acid and vitamin E in the thalassemia patients were found to be considerably lower compared to normal subjects. The activities of enzymatic antioxidants viz. catalase, glutathione peroxidase and glutathione reductase were found to be drastically reduced in untreated Ebeta- and beta-thalassemic patients when compared to normal subjects. However, the activity of superoxide dis-mutase was found to be increased in both types of untreated thalassemic patients when compared to normal individuals. An increase in superoxide dismutase and a decrease in catalase activity reflects the presence of a severe oxidative stress situation in the erythrocytes of the untreated transfusion dependent Ebeta- and beta-thalassemia patients. Changes in erythrocyte membrane protein pattern in untreated Ebeta- and beta-thalassemia patients when compared to normal erythrocyte further confirm the presence of continued oxidative stress in the ailing thalassemic erythrocytes. All these changes in the antioxidant status as well as the changes in the erythrocyte membrane proteins are ameliorated to considerable extent when the transfusion-dependent Ebeta- and beta-thalassemia patients were treated with vitamin E at a dose of 10 mg/kg/day for a period of four weeks. The patients during the treatment period did not exhibit any side effects and gained in body weight indicating a healthy status. The present study reveals that the lipophilic antioxidant vitamin E could be useful in the management of transfusion-dependant Ebeta- and beta-thalassemia patients.

Subclassification of HbS syndrome: is it necessary?

Sickle beta-thalassaemia (S beta-thalassaemia) is a condition, which results from coinheritance of a sickle cell gene and a beta-thalassaemia gene. The clinical phenotype depends on the type of beta-thalassaemia gene (beta+ or beta(o)). There are several similarities in clinical and haematological features, which sometimes pose a difficulty in correct diagnosis. A definitive diagnosis is required in order to initiate early supportive treatment in patients with homozygous sickle cell disease (SS disease) and to define the later clinical course. Forty-seven cases of haemoglobin sickle syndrome (HbS syndrome) were studied. The clinico-haematological features and high-performance liquid chromatography (HPLC) results from 17 patients with S beta-thalassaemia were compared with those of SS disease (10 patients). Splenomegaly was more commonly found in patients with S beta-thalassaemia. Among the haematological features, red blood cell counts and HbA2 levels were significantly higher in patients with S beta-thalassaemia, while red cell indices, such as MCV, MCH were significantly lower than those seen SS disease. MCHC, PCV total haemoglobin (Hb), HbS, A and HbF were similar in the two groups.

Phenotype score to grade the severity of thalassemia intermedia

OBJECTIVE

Thalassemia intermedia is an ill-defined group of thalassemia patients with severity in between thalassemia major and asymptomatic carriers. The severity of cases varies greatly. With availability of information about genetic modifiers of beta-thalassemia phenotype, attempts are being made to study genotype phenotype correlation in thalassemia intermedia.

METHODS

The first important step in genotype, phenotype correlation is well-defined phenotypes. Severity of thalassemia intermedia can not be graded only on haemoglobin level and age of presentation. The authors have developed a phenotype scoring system to subclassify thalassemia intermedia patients into 3 groups, viz, mild, moderate and severe.

RESULT

This phenotype scoring system appears to grade the severity correctly depending on various clinical features like age of presentation, severity of anaemia, growth retardation, bone marrow hyperplasia, need of blood transfusions and splenectomy.

CONCLUSION

The classification of thalassemia intermedia will be useful for genotype phenotype correlation, to develop management guidelines for the subgroups and to try new treatment modalities like hydroxyurea, erythropoetin etc.

Sleep disruption and objective sleepiness in children with beta-thalassemia and congenital dyserythropoietic anemia

BACKGROUND

Sleep fragmentation and periodic leg movement syndrome (PLMS) have been reported in adults with iron deficiency anemia. Little is known about sleep function and daytime sleepiness in children with chronic anemia such as beta-thalassemia or congenital dyserythropoietic anemia type 1 (CDA-1).

OBJECTIVES

To investigate if children and adolescents who have beta-thalassemia (major or intermedia) or CDA-1 experience sleep fragmentation and objective daytime sleepiness and also to investigate if children and adolescents with beta-thalassemia have obstructive sleep apnea.

METHODS

Ten patients (7 males and 3 females) with beta-thalassemia (mean [SD] age, 10.4 [7.3] years), 10 patients (7 males and 3 females) with CDA-1 (mean [SD] age, 13.5 [5.1] years), and 13 healthy volunteer control children(7 males and 6 females) (mean [SD] age, 10 [4] years) underwent nocturnal polysomnographic studies. A multiple sleep latency test was performed for 6 patients who had beta-thalassemia and 8 patients who had CDA-1.

RESULTS

Both patient groups, that is, those who had beta-thalassemia and those who had CDA-1, had multiple arousals during sleep (mean [SD], 27.8 [11.4] events per hour and 23.8 [11.8] events per hour, respectively) compared with the control subjects (12.1 [6.6] events per hour) (P<.002). Thirty-eight percent (10.6 events per hour) of the arousals in patients with beta-thalassemia and 25% (6.0 events per hour) of the arousals in patients with CDA-1 were induced by periodic limb movements during sleep. In the control group, most (98%) arousals were spontaneous and unrelated to any definable event. The multiple sleep latency test average was 7.8 minutes for patients with beta-thalassemia (n = 6) and 10.7 minutes for patients with CDA-1 (n = 8). Five patients with beta-thalassemia and 4 patients with CDA-1 underwent a second polysomnographic study on the next night to confirm reproducibility. There was no significant change in the total number or index of arousals and no difference in the severity of the periodic limb movements during sleep compared with the results of the first polysomnographic study.

CONCLUSION

Children and adolescents with beta-thalassemia or CDA-1 have evidence of impaired sleep function that is partially due to periodic limb movements during sleep and arousals that result in objective diurnal sleepiness.

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.

Bone marrow transplantation in thalassaemia patients in Shiraz, Islamic Republic of Iran

We report the results of allogeneic bone marrow transplantation in 26 female and 37 male patients with beta-thalassaemia major (age range: 2-17 years), performed at Namazi Hospital over the period 1992-99. In all cases, standard conditioning and immunosuppressive regimens were employed. Currently, 50 patients remain thalassaemia-free, 9 of whom have developed chronic graft-versus-host disease. There were 8 deaths among the 13 unsuccessful transplant cases: 4 due to acute uncontrollable graft-versus-host disease, and 4 to non-transplant-related causes such as hypoglycaemia, hypersensitivity reactions and advanced disease. We conclude that allogeneic bone marrow transplantation is an effective therapy for the treatment of beta-thalassaemia major, particularly for patients classified as classes I and II.

Prediction of adverse outcomes in children with sickle cell disease

BACKGROUND

The ability to identify infants with sickle cell anemia who are likely to have severe complications later in life would permit accurate prognostication and tailoring of therapy to match disease-related risks and facilitate planning of clinical trials. We attempted to define the features of such babies by following the clinical course of 392 children with sickle cell disease from infancy to about the age of 10 years.

METHODS

We analyzed the records of 392 infants who received the diagnosis of homozygous sickle cell anemia or sickle cell-Beta(0)-thalassemia before the age of six months and for whom comprehensive clinical and laboratory data were recorded prospectively; data were available for a mean (+/-SD) of 10.0+/-4.8 years. Results obtained before the age of two years were evaluated to determine whether they predicted the outcome later in life.

RESULTS

Of the 392 infants in the cohort, 70 (18 percent) subsequently had an adverse outcome, defined as death (18 patients [26 percent]), stroke (25 [36 percent]) frequent pain (17 [24 percent]), or recurrent acute chest syndrome (10 [14 percent]). Using multivariate analysis, we found three statistically significant predictors of an adverse outcome: an episode of dactylitis before the age of one year (relative risk of an adverse outcome, 2.55; 95 percent confidence interval, 1.39 to 4.67), a hemoglobin level of less than 7 g per deciliter (relative risk, 2.47; 95 percent confidence interval, 1.14 to 5.33), and leukocytosis in the absence of infection (relative risk, 1.80; 95 percent confidence interval, 1.05 to 3.09).

CONCLUSIONS

Three easily identifiable manifestations of sickle cell disease that may appear in the first two years of life (dactylitis, severe anemia, and leukocytosis) can help to predict the possibility of severe sickle cell disease later in life.

Levels of Hb A2 in heterozygotes and homozygotes for beta-thalassemia mutations: influence of mutations in the CACCC and ATAAA motifs of the beta-globin gene promoter

The author summarizes the Hb A2 levels in over 600 beta-thalassemia heterozygotes with 32 different base changes or frameshifts and in 22 heterozygotes for 1 of 5 large deletions. Three major groups are recognized: persons with beta zero-thalassemia or beta (+)-thalassemia (severe) have Hb A2 levels between 4.5 and 5.5%, those with mild beta (+)-thalassemia alleles have levels between 3.6 and 4.2%, with still lower values for those with silent mutations. High values were observed in subjects with the 2 mild beta + alleles with mutations in the beta-globin gene promoter (-88, C-->T and -29, A-->G); unusually high Hb A2 values were also present in several -88 and -29 homozygotes. Data for several members of 8 families in which the -88 (C-->T) or the -29 (A-->G) mutation, or the -1,393-bp deletion, is present in cis or in trans to a delta-globin gene mutation support earlier observations that an increase in delta-chain synthesis occurs in cis to either one of these 3 alleles. A review of these data confirms the suggestion that the increase in Hb A2 levels results from at least two mechanisms: in a posttranslational system, the formation of alpha delta-dimers is promoted when excess alpha-chains are available, while certain promoter mutations increase the transcription of the delta-globin gene in cis because of a change in the binding of transcription factors.

Longitudinal monitoring of bone mineral density in thalassemic patients. Genetic structure and osteoporosis

The changes in bone mineral density (BMD) measured by single photon absorptiometry (SPA) using two observations conducted over a period of 2 years were examined in 54 thalassemic subjects [30 F(A) and 24 M(B)] with a chronological age ranging from 2.6 to 22.6 years and in 27 sex- and age-matched controls (C). Each category (A, B and C) was divided into three groups according to pubertal signs: pre-pubertal subjects (A1, B1 and C1); peri-pubertal subjects (A2, B2 and C2) and pubertal subjects from the first observation (A3, B3 and C3). Furthermore, each group of patients was divided into sub-groups on the basis of haematological phenotypes, those with a more severe form were called beta0/beta0 while those with other forms were called "others". The most significant findings were the following: the presence of a more severe reduction of the bone mineral density in patients with the beta0/beta0 phenotype than in patients with the "others" phenotype; patients with hypogonadism corresponded to the beta0/beta0 phenotype, while those with spontaneous puberty corresponded to the "others" phenotype. In conclusion, since puberty and the degree of bone mineral density are related to the haematological phenotype, puberty (spontaneous or induced) positively influences the bone mineral density only at the start of puberty, while subsequently, the degree of osteoporosis is the expression of widespread and chronic systemic damage due to the haematological phenotype.

Relative levels of alpha-, beta-, and gamma-mRNA from patients with severe and intermediate beta-thalassemia major

We have determined the relative quantities of gamma- and beta-mRNAs and the alpha/beta-mRNA ratios in 37 patients with beta-thalassemia major with specific genotypes, namely 8 with a homozygosity for codon (CD) 39 (C-->T), 7 with a homozygosity for IVS-I-110 (G-->A), 5 with a homozygosity for IVS-I-6 (T-->C), for 15 patients with compound heterozygosities for 2 of these 3 mutations, and for 2 patients with the IVS-I-110 (G-->A)/-87 (C-->G) mutations. None had an alpha-thalassemia. Twelve patients had thalassemia intermedia and the remainder, transfusion-dependent severe conditions. Differences in phenotype were observed for compound heterozygotes involving the IVS-I-6 (T-->C) mutation in combination with either the IVS-I-110 (G-->A) or the CD 39 (C-->T) mutations: patients with thalassemia intermedia had a lower alpha/beta-mRNA ratio, about half of that of the patients with severe beta-thalassemia major. This might suggest a higher beta-mRNA synthesis in some patients than in others with the same genotype; mutations in promoter, enhancer, and/or locus control region sequences may be responsible for these differences. In vitro chain synthesis data were too incomplete to be helpful in this study. The RT-PCR procedure allowed the separation of abnormal (extended) mRNA from normal beta-RNA in subjects carrying the IVS-I-110 (G-->T) mutation. The relative quantities of this beta Th-mRNA (% of beta A + beta Th) were determined by scanning of the appropriate autoradiograms; they averaged 25% for homozygotes and about 4% for heterozygotes, indicating a considerable instability of the message.

A novel (delta beta)(0)-thalassemia due to a approximately 30-kb deletion observed in a Turkish family

A new deletion of the beta-globin gene cluster was characterized in a Turkish family. A 6-year-old male and his father were heterozygotes for this deletion. They presented with mild hypochromic microcytic anemia associated with elevated Hb F (15%) and normal Hb A2 levels (2.0%). This newly described Turkish type (delta beta)(0) thalassemia has a deletion of about 30 kb. The 5' breakpoint of this deletion starts approximately 1.5 kb downstream of an enhancer-like sequence of the A gamma-globin gene. The 3' endpoint is located in the L1 repeat sequence (Kpnl site) 3' to the beta-globin gene. The new deletion (Turkish type 3) is quite similar to that of the Indian (delta beta)(0)-thalassemia deletion in size and 5' breakpoint. However, the 3' endpoint in this new deletion is 2.5 kb shorter than the Indian type.

Bone marrow transplantation in thalassemia

Early trials of allogeneic bone marrow transplantation (BMT) for homozygous beta-thalassemia and the analyses of results of transplantation in patients less than 16 years old have allowed us to identify three classes of risk based on the following criteria: (a) hepatomegaly, (b) presence of liver fibrosis at histological examination, and (c) quality of chelation treatment given before transplant. Patients with none of these adverse criteria were assigned to Class 1; patients with either one or two adverse criteria comprised Class 2; and patients for whom all three criteria were adverse constituted Class 3. Most patients older than 16 years have disease characteristics that place them in Class 3, with very few falling into Class 2. All patients with a histocompatibility leukocyte antigen (HLA)-identical donor are actually assigned to one of two conditioning regimens on the basis of the class they belong to at the time of BMT and independently of age. For Class 1, Class 2, and Class 3 patients, the probabilities of survival and event-free survival are 95 and 90%, 86 and 82%, and 87 and 63%, respectively. For those patients older than 16 years at the time of transplant, the probabilities of survival and of event-free survival are 78 and 74%, respectively. Allogeneic BMT is currently the only rational therapeutic modality for the eradication of beta-thalassemia.

Thalassaemia and other haemoglobinopathies in general practice

Haemoglobinopathies are now common in Australia following the migration of people from areas of high prevalence. This article gives practical advice on the management of patients incidentally found to be heterozygotes for the more common forms and also outlines complications of major haemoglobinopathies that are seen in family practice.

Thalassemia: pathophysiology of red cell changes

The thalassemias are extremely heterogeneous in terms of their clinical severity, and their underlying pathophysiology relates directly to the extent of accumulation of excess unmatched globin chains: alpha in beta thalassemia and beta in the alpha thalassemias. However, the accumulation of each separate globin chain affects red cell membrane material properties and the state of red cell hydration very differently. These observations presumably account for the varying extent of ineffective erythropoiesis and peripheral blood hemolysis in the major variants of thalassemia. The thalassemias are a worldwide group of inherited disorders of globin-chain synthesis that developed in multiple geographic regions, probably because they provided partial protection against malaria. In normal assembly of adult hemoglobin (HbA-alpha 2 beta 2), alpha and beta globin are synthesized by genes on different chromosomes, whereas heme is synthesized primarily on mitochondria. The synthesis of these chains is very tightly coordinated so that the ratio of alpha globin to beta globin (beta in this case including the beta-like globins delta and gamma) is normally 1 +/- 0.05. Furthermore, specific erythroid proteases are designed to attack and destroy excess alpha or beta globin chains, demonstrating the deleterious impact of the accumulation of excess unmatched globin chains. In beta thalassemia, production of beta globin decreases and excess alpha globin accumulates. In alpha thalassemia, on the other hand, this process occurs in reverse. Perhaps in these disorders more than any others, molecular biologists have documented the deletional and transcriptional events leading to diminished synthesis of specific classes of globin chains.(ABSTRACT TRUNCATED AT 250 WORDS)

[Diagnosis of hemoglobinopathies and thalassemias]

During recents the number of immigrants to Norway from Africa and South East Asia has risen considerably. These persons come from countries with a high prevalence of haemoglobinopathies. Most of the immigrants with haemoglobinopathies are silent carriers, but some have a serious disease or have offspring with serious disease. This situation calls for increasing awareness and knowledge of haemoglobinopathies, especially the thalassemias and sickle cell trait. Genetic counselling is particularly important, since the majority of these immigrants marry within small ethnic groups. This paper gives a survey of the most frequent haemoglobinopathies likely to be encountered in Norway.

Direct carrier detection and prenatal diagnosis of Sicilian and Spanish (delta beta)zero-thalassemias

We describe a direct method for detection of the Spanish and Sicilian (delta beta)zero-thalassemias. This method is based on the use of the deletion-junction sequences to design specific PCR primers. It permits a rapid screening of heterozygotes in populations at risk and provides a useful tool for early prenatal diagnosis of these forms of thalassemia.