Update on Thalassemia: Clinical Care and Complications

Predicting Thalassemia Using Feature Selection Techniques: A Comparative Analysis

Thalassemia represents one of the most common genetic disorders worldwide, characterized by defects in hemoglobin synthesis. The affected individuals suffer from malfunctioning of one or more of the four globin genes, leading to chronic hemolytic anemia, an imbalance in the hemoglobin chain ratio, iron overload, and ineffective erythropoiesis. Despite the challenges posed by this condition, recent years have witnessed significant advancements in diagnosis, therapy, and transfusion support, significantly improving the prognosis for thalassemia patients. This research empirically evaluates the efficacy of models constructed using classification methods and explores the effectiveness of relevant features that are derived using various machine-learning techniques. Five feature selection approaches, namely Chi-Square (χ2), Exploratory Factor Score (EFS), tree-based Recursive Feature Elimination (RFE), gradient-based RFE, and Linear Regression Coefficient, were employed to determine the optimal feature set. Nine classifiers, namely K-Nearest Neighbors (KNN), Decision Trees (DT), Gradient Boosting Classifier (GBC), Linear Regression (LR), AdaBoost, Extreme Gradient Boosting (XGB), Random Forest (RF), Light Gradient Boosting Machine (LGBM), and Support Vector Machine (SVM), were utilized to evaluate the performance. The χ2 method achieved accuracy, registering 91.56% precision, 91.04% recall, and 92.65% f-score when aligned with the LR classifier. Moreover, the results underscore that amalgamating over-sampling with Synthetic Minority Over-sampling Technique (SMOTE), RFE, and 10-fold cross-validation markedly elevates the detection accuracy for αT patients. Notably, the Gradient Boosting Classifier (GBC) achieves 93.46% accuracy, 93.89% recall, and 92.72% F1 score.

Epidemiologic Trends of Thalassemia, 2006-2018: A Nationwide Population-Based Study

Thalassemia is the most common form of hereditary anemia. Here, we aimed to investigate the 13-year trend of the epidemiologic profiles and risk of comorbidities in thalassemia using a nationwide population-based registry in Korea. Diagnosis of thalassemia, the comorbidities and transfusion events in patients with thalassemia were identified in the Korean National Health Insurance database, which includes the entire population. The prevalence of thalassemia increased from 0.74/100,000 in 2006 to 2.76/100,000 in 2018. Notably, the incidence rate has nearly doubled in the last 2 years from 0.22/100,000 in 2016 to 0.41/100,000 in 2018. The annual transfusion rate gradually decreased from 34.7% in 2006 to 20.6% in 2018. Transfusion events in patients with thalassemia were significantly associated with the risk of comorbidities (diabetes: odds ratio [OR] = 3.68, 95% confidence interval [CI] = 2.59–5.22; hypertension: OR = 3.06, 95% CI = 2.35–4.00; dyslipidemia: OR = 1.72, 95% CI = 1.22–2.43; atrial fibrillation: OR = 3.52, 95% CI = 1.69–7.32; myocardial infarction: OR = 3.02, 95% CI = 1.09–8.38; stroke: OR = 3.32, 95% CI = 2.05–5.36; congestive heart failure: OR = 2.83, 95% CI = 1.62–4.97; end-stage renal disease: OR = 3.25, 95% CI = 1.96–5.37). Early detection of comorbidities and timely intervention are required for the management of thalassemia.

Thalassemia, a human blood disorder

A group of inherited blood defects is known as Thalassemia is among the world's most prevalent hemoglobinopathies. Thalassemias are of two types such as Alpha and Beta Thalassemia. The cause of these defects is gene mutations leading to low levels and/or malfunctioning α and β globin proteins, respectively. In some cases, one of these proteins may be completely absent. α and β globin chains form a globin fold or pocket for heme (Fe++) attachment to carry oxygen. Genes for alpha and beta-globin proteins are present in the form of a cluster on chromosome 16 and 11, respectively. Different globin genes are used at different stages in the life course. During embryonic and fetal developmental stages, γ globin proteins partner with α globin and are later replaced by β globin protein. Globin chain imbalances result in hemolysis and impede erythropoiesis. Individuals showing mild symptoms include carriers of alpha thalassemia or the people bearing alpha or beta-thalassemia trait. Alpha thalassemia causes conditions like hemolytic anemia or fatal hydrops fetalis depending upon the severity of the disease. Beta thalassemia major results in hemolytic anemia, growth retardation, and skeletal aberrations in early childhood. Children affected by this disorder need regular blood transfusions throughout their lives. Patients that depend on blood transfusion usually develop iron overload that causes other complications in the body systems like renal or hepatic impairment therefore, thalassemias are now categorized as a syndrome. The only cure for Thalassemias would be a bone marrow transplant, or gene therapy with currently no significant success rate. A thorough understanding of the molecular basis of this syndrome may provide novel insights and ideas for its treatment, as scientists have still been unable to find a permanent cure for this deadly disease after more than 87 years since it is first described in 1925.

Providers' Perspectives on Treating Patients With Thalassemia

In recent years, California has experienced a steady rise in Asian immigration which has led to a corresponding increased prevalence of clinically significant thalassemia in this state. As part of the Public Health Research, Education and Surveillance for Hemoglobinopathies emoglobinopathies project, a survey was developed to collect information from California providers who care for thalassemia patients in an effort to better understand their practice patterns, barriers to providing care, and educational needs. When asked about educational needs, providers most frequently expressed a desire for care and management guidelines (65.3%), health educational materials for patients (47.2%), and information on complications and clinical outcomes (32.1%). Only one quarter of providers (24.0%) reported that all of their thalassemia patients have a coordinated care plan. The increase in California thalassemia cases highlights the importance of provider knowledge to effectively serve the patients in their communities. Provider education and dissemination of treatment standards can not only improve knowledge about the disease but also increase awareness about the importance of coordinating care among a multidisciplinary team of specialists. Improvement in these areas will help achieve the overarching goal of better outcomes and quality of life for patients with thalassemia.

Study of alloimmunization and autoimmunization in Iranian β-thalassemia major patients

Background:

Thalassemia is one of the most common monogenic disorders characterized by reduced production of globin chains. Although regular red blood cell (RBC) transfusion support is the main treatment for these patients, it may be associated with complications such as RBC alloimmunization.

Aim:

The study aimed to determine the incidence of alloimmunization and autoimmunization to RBC antigens in β-thalassemia major patients from Zanjan, Zanjan Province, Iran.

Materials and Methods:

A total of 49 β-thalassemia major patients comprising 24 females and 25 males (mean age: 18.59 ± 8.16 years; range: 2-40 years) from Northwest Iran were included in a cross-sectional study. Alloantibody screening and identification were done using 3-cell and 10-cell reagent red blood cells, respectively. Autoantibody detection was performed using direct Coomb's test.

Results:

The incidence of alloimmunization was 16.32% with 10 alloantibodies identified in 8 patients. The most common clinically significant alloantibody identified in alloimmunized patients was anti-Kell (K-antigen) (60%) followed by anti-Rhesus (Rh) (E, c-antigens). The rate of alloimmunization was significantly lower in patients transfused with leukoreduced RBCs compared with those transfused with nonleukoreduced RBCs (9.53% vs 57.14%, P = 0.001). There was no significant correlation between alloantibody formation and the age, gender, hemoglobin levels, number of transfused units, and splenectomy.

Conclusion:

Transfusion of leukoreduced and phenotypically matched red blood cells for Kell (K) and Rh (E, c) antigens may help reduce the alloimmunization rate in Iranian β-thalassemia major patients. Moreover, autoimmunization to RBC antigens was rare in our patients.

Thalassemia Phenotypes and Genotypes in Taiwan: A Retrospective Study Based on Thalassemia Screening of Young Men for Military Conscription

Prenatal thalassemia studies from Taiwan show that one-third of fetuses with genetic abnormalities have β-thalassemia major (β-TM). However, the phenotypes and genotypes of adult thalassemia warrant further investigation. From September 2006 to April 2014, 741 male candidates drafted for military service with mean corpuscular volume (MCV) <80 fL and serum ferritin >20 µg/L were analyzed. The results showed that the detection rates of α- and β-thalassemia (α- an β-thal) were 50.20% (372/741) and 49.12% (364/741), respectively. Only five patients (0.67%) were diagnosed with both α- and β-thal. The - -(SEA)/αα mutation was found in 76.88% (286/372) of α-thal patients. Heterozygous mutations in IVS-II-654 (C > T) and codons 41/42 (-TCTT) accounted for 55.77% (203/364) of β-thal cases. The leukocyte counts for α- and β-thal were 6241.74 ± 1552.99 and 6622.87 ± 1814.41 × 10(9)/L, respectively (p = 0.007). The α-thal patients had lower red blood cell (RBC) mass (5.85 ± 0.44 × 10(12)/L vs. 6.09 ± 0.45 × 10(12)/L; p < 0.001) and higher hemoglobin (Hb) (12.82 ± 0.72 vs. 12.35 ± 0.71 g/dL; p < 0.001) than β-thal patients. Mean serum ferritin values were 169.67 and 241.36 µg/L, respectively, in α- and β-thal patients (p < 0.001), indicating more profound ineffective erythropoiesis in β-thal. Only four of the 741 patients underwent further hematological follow-up. Our study suggests that iron overload might be a potential problem in β-thal patients; therefore, regular follow-up is highly recommended.

Prevalence of hemoglobinopathies in school children: the importance of using confirmatory methods

<p>The hemoglobinopathies are included among the most common genetic diseases in the world. In Brazil, hemoglobinopathies are related to the diversity of racial backgrounds and the degree of interbreeding. The study focused on the prevalence of hemoglobinopathies using conventional and confirmatory laboratory tests in children from public schools in Ribeirão Preto-SP. The study involved the participation of 427 children between six and nine years of age. Hematologic evaluation, hemoglobin electrophoresis on cellulose acetate at alkaline pH, quantification of hemoglobin fractions by high performance liquid chromatography (HPLC) and detection of -α^3.7 deletion for α thalassemia by polymerase chain reaction were performed. The results of hemoglobin electrophoresis on cellulose acetate and HPLC of the children studied showed the presence of 30 children (7%) with hemoglobinopathies. Eleven children presented results indicating suspicion of S/β-thalassemia; their parents and/or siblings were evaluated and confirmed the presence of only Hb S. The analysis of deletion -α^3.7to characterize α-thalassemias sampling performed on 207 participants identified 26 children (12.6%) with deletion -α^3.7. Thus, 54 (12.6%) of the children studied present this genetic alteration. For the detection of α-thalassemias it is necessary to use confirmatory methods such as molecular analysis and evaluation of family members in doubtful cases to facilitate genetic counseling in families, in which deletion -α^3.7 is more frequent in Brazil.</p>

Marital Status and Fertility in Adult Iranian Patients with β-Thalassemia Major

Expecting a family is an important component and a great goal for better quality of life for most of adults with β-thalassemia major. The aim of the present study was to examine the marital status of adults with β-thalassemia major. This cross-sectional study examined the marital status of patients with transfusion-dependent β-thalassemia aged over 15 years. Patients' demographic characteristics including age, gender, marital status, duration of marriage, divorce, having or not having children and spouse's health status were recorded. Information about the disease including cardiac and endocrine complications, ferritin level, splenectomy and viral hepatitis were also recorded. Of 228 patients with transfusion-dependent β-thalassemia major aged over 15 years who were treated at this medical center, 32 (14 %) were married. The mean age of married patients was 25.18 ± 4.74 years. Among the married patients, 8 (25 %) were females and 24 (75 %) patients were males. The mean age of marriage was 22.76 ± 4.16 years. The minimum and maximum marriage age was 15 and 33 years, respectively. The median duration of marriage was one year with the range from 3 months to 11 years. Only 8 (25 %) patients (one female and seven males) had children. Therapeutic advances have led to significantly increased survival and improved quality of life and fertility of patients with β-thalassemia major. According to the results, 14 % of patients over 15 years were married which was slightly higher as compared with other similar studies.

εGγAγδβ0-thalassemia: a rare but clinically significant cause of hemolytic anemia in infants

Normal hemoglobin is made of a tetramer of 2 α-globin and 2 β-globin polypeptide chains. Deletions in the β-globin gene cluster can range from a few hundred base pairs to loss of the entire cluster resulting in rare, but clinically significant, thalassemias. One such entity is εGγAγδβ0-thalassemia, a condition that presents within the first few weeks of life as a Coombs-negative hemolytic anemia and is not identified on routine newborn screening or hemoglobin electrophoresis.

Combining gene therapy and fetal hemoglobin induction for treatment of β-thalassemia

β-thalassemias are caused by nearly 300 mutations of the β-globin gene, leading to a low or absent production of adult hemoglobin (HbA). Two major therapeutic approaches have recently been proposed: gene therapy and induction of fetal hemoglobin (HbF) with the objective of achieving clinically relevant levels of Hbs. The objective of this article is to describe the development of therapeutic strategies based on a combination of gene therapy and induction of HbFs. An increase of β-globin gene expression in β-thalassemia cells can be achieved by gene therapy, although de novo production of clinically relevant levels of adult Hb may be difficult to obtain. On the other hand, an increased production of HbF is beneficial in β-thalassemia. The combination of gene therapy and HbF induction appears to be a pertinent strategy to achieve clinically relevant results.

Clinical characteristics of pediatric thalassemia in Korea: a single institute experience

Few literatures have elaborated on the clinical characteristics of children with thalassemia from low-prevalence areas. A retrospective analysis was conducted on children genetically confirmed with thalassemia at Seoul National University Children's Hospital in Korea. Nine children (1α thalassemia trait, 6β thalassemia minor, 2β thalassemia intermedia) were diagnosed with thalassemia at median age of 4.3 yr old with median hemoglobin of 9.7 g/dL. Seven (78%) children were incidentally found to be anemic and only 2 with β thalassemia intermedia had presenting symptoms. Five children (56%) were initially misdiagnosed with iron deficiency anemia. Despite the comorbidities due to α thalassemia mental retardation syndrome, the child with α thalassemia trait had mild hematologic profile. Children with β thalassemia intermedia had the worst phenotypes due to dominantly inherited mutations. None of the children was transfusion dependent and most of them had no complications associated with thalassemia. Only 1 child (11%) with codon 60 (T→A) mutation of the HBB gene needed red blood cell transfusions. He also had splenomegaly, cholelithiasis, and calvarial vault thickening. Pediatricians in Korea must acknowledge thalassemia as a possible diagnosis in children with microcytic hypochromic hemolytic anemia. High level of suspicion will allow timely diagnosis and managements.

Hemolytic anemia in adults: main causes and diagnostic procedures

Hemolytic anemia is not an exceptional situation in adults. Although establishing the hemolytic mechanism of an anemia is usually rather easy, finding the etiology may be quite difficult as both hereditary (corpuscular) and acquired causes of hemolytic anemia may occur during adulthood. The diagnosis of hemolytic anemia, therefore, requires a multistep procedure taking into account both the patient's and family history, a careful analysis of the blood smear and a direct antiglobulin test. Based on these first data, the diagnostic procedure may then require more specific tests whose indications are discussed in this review.

Alternative options for DNA-based experimental therapy of β-thalassemia

INTRODUCTION

Beta-thalassemias are caused by more than 200 mutations of the β-globin gene, leading to low or absent production of adult hemoglobin. Achievements have been made with innovative therapeutic strategies for β-thalassemias, based on research conducted at the levels of gene structure, transcription, mRNA processing and protein synthesis.

AREAS COVERED

The objective of this review is to describe the development of therapeutic strategies employing viral and non-viral DNA-based approaches for treatment of β-thalassemia.

EXPERT OPINION

Modification of β-globin gene expression in β-thalassemia cells has been achieved by gene therapy, correction of the mutated β-globin gene and RNA repair. In addition, cellular therapy has been proposed for β-thalassemia, including reprogramming of somatic cells to generate induced pluripotent stem cells to be genetically corrected. Based on the concept that increased production of fetal hemoglobin (HbF) is beneficial in β-thalassemia, DNA-based approaches to increase HbF production have been optimized, including treatment of target cells with lentiviral vectors carrying γ-globin genes. Finally, DNA-based targeting of α-globin gene expression has been applied to reduce the excess of α-globin production by β-thalassemia cells, one of the major causes of the clinical phenotype.

Molecular study and genotype/phenotype correlation of β Thalassemia in Malaysia

INTRODUCTION

To study the ß-gene mutations spectrum, the genotype/phenotype correlation, the modulatory effect of co-inherited factors such as α-gene mutations and of Xmn1 polymorphism in a large cohort of Malaysian patients.

METHODS

A total of 264 cases clinically diagnosed as Thalassemia major (TM) (111), Thalassemia intermedia (21), HbE-β Thalassemia (131), and 1 HbE homozygous were studied. The detection of α and ß gene mutations and characterization of Xmn1 polymorphism were performed by multiplex PCR, amplification refractory mutation system (ARMS), DNA sequencing, and restriction fragment length polymorphism (RFLP)-PCR.

RESULTS

A total of 19 ß Thalassemia mutations were characterized. CD26 and CD41/42 were the most common found in the Malay and Chinese population, respectively. The sensitivity of the clinical diagnosis for β TM, thalassemia intermedia, and HbE/β thalassemia was 94.0%, 15.2%, and 89.2%, respectively. Patients with Xmn1 heterozygosity [+/-] required less frequent transfusion compared with those without the polymorphism. Co-inheritance of α-thalassemia alleviates the severity of HbE-β thalassemia in our cohort.

CONCLUSION

Molecular analysis should be used for a better diagnosis and management of β thalassemia.