Thalassemias: General Overview

Article written and reviewed by Dr Luca Moretti

Thalassemias are a heterogeneous group of inherited hemoglobinopathies characterized by reduced or absent synthesis of one or more globin chains that make up hemoglobin. In clinically significant forms, globin-chain imbalance may cause ineffective erythropoiesis, microcytic anemia, hemolysis and, in more severe or transfused forms, systemic manifestations and complications of iron overload.

Arising from the clinical and genetic identification of different mutations affecting the genes encoding globin chains (alpha, beta, delta and gamma), thalassemias are classically divided into alpha-thalassemia and beta-thalassemia, alongside rarer forms (delta-beta, gamma-delta-beta, epsilon-gamma, epsilon-gamma-delta-beta, thalassemias with combined defects or associated with other hemoglobinopathies, such as HbE, Hb Lepore, Hb Constant Spring and others). Clinical heterogeneity is extremely pronounced, ranging from minimally symptomatic carrier states to severe transfusion-dependent forms with early impairment of growth and risks of endocrine-metabolic, skeletal, cardiac, infectious and neoplastic complications.

Understanding the molecular basis, pathophysiology, classification and general principles of thalassemia management is essential for approaching the diagnosis and treatment of the different forms, which are discussed in detail in the individual monographs.

Structure and function of hemoglobin

To understand the pathophysiology of thalassemias fully, it is essential to begin with the structure and function of hemoglobin. Hemoglobin is a tetrameric protein composed of four globin chains associated with one another, each bound to a heme group capable of transporting one oxygen molecule. The type of globin chains composing the molecule changes during ontogenetic development and determines the different physiologic forms of hemoglobin at the various stages of life.

During the earliest stages of embryonic development, so-called “embryonic” hemoglobins predominate, including Hb Gower I (composed of two zeta and two epsilon chains, ζ₂ε₂), Hb Gower II (α₂ε₂) and Hb Portland (ζ₂γ₂). These forms have a limited duration and are replaced, as early as the second trimester of pregnancy, by fetal hemoglobin (HbF), composed of two alpha and two gamma chains (α₂γ₂).

HbF is characterized by a significantly higher oxygen affinity than adult hemoglobin. This feature is fundamental for oxygen transfer from mother to fetus across the placenta: the high oxygen affinity of HbF enables it to acquire oxygen from maternal hemoglobin, ensuring effective delivery to fetal tissues even under conditions of relative hypoxia. The molecular basis lies in the different structure of the gamma chains, which reduces the molecule’s ability to bind 2,3-diphosphoglycerate (2,3-DPG), a negative regulator of hemoglobin oxygen affinity.

After birth, progressive activation of the β gene and reduced expression of the γ genes lead to replacement of HbF by the principal adult hemoglobin (HbA, α₂β₂), which accounts for approximately 97% of total hemoglobin in healthy adults. This composition, two alpha and two beta chains, provides an optimal balance between oxygen affinity and release because of greater sensitivity to 2,3-DPG and a stable structure capable of withstanding environmental changes and the functional demands of adult metabolism.

Alongside HbA, a small proportion, approximately 2-3%, of hemoglobin A2 (HbA2, α₂δ₂) and residual HbF (<1% in adults, with reference intervals depending on the method and laboratory) complete the physiologic hemoglobin profile. The presence of the different forms of hemoglobin is precisely regulated by epigenetic mechanisms and gene switching, which ensure production of the globin chains most appropriate to the metabolic requirements of each stage of life.

Correct combination of the globin chains is essential not only for the molecular stability of hemoglobin, but especially for balancing its key function: transporting oxygen to tissues and facilitating its release when needed. Quantitative defects in globin synthesis cause thalassemias and may result in chain imbalance, abnormal tetramers or toxic free chains. Structural abnormalities instead constitute distinct hemoglobinopathies and produce variable functional consequences, sometimes none.

Etiology and Genetics

The etiology of thalassemias lies in genetic abnormalities that impair globin-chain synthesis; in the great majority of cases they are inherited, although rare de novo events have been documented. Clinical expression, severity and type of thalassemia depend on the nature of the mutation, the number of genes involved and interactions with any other hemoglobin variants.

The globin-chain genes are located on two different chromosomes: chromosome 16 contains the genes responsible for alpha-chain synthesis (HBA1 and HBA2), whereas chromosome 11 contains the beta (HBB), delta (HBD), gamma (HBG1, HBG2) and epsilon (HBE1) genes. The diploid genome contains four alpha genes, two beta genes, two delta genes, four gamma genes in total (two HBG1 and two HBG2) and two epsilon genes.

Mutations causing thalassemias are divided into:

• Gene deletions: typical of alpha-thalassemias, they consist of loss of one or more alpha genes, causing reduced alpha-chain synthesis whose extent depends on the number and type of alleles involved. The phenotype depends mainly on the total number of inactivated alpha-globin alleles, their arrangement in cis or trans, and the specific abnormality: inactivation of a single copy is generally asymptomatic, whereas loss of all four leads to hydrops fetalis due to Hb Bart’s, which is almost invariably fatal without intrauterine treatment and specialist perinatal care.
• Point, splicing, frameshift or promoter mutations: typical of beta-thalassemias, they cause reduced (β+) or absent (β0) beta-chain synthesis. These mutations may involve the transcription start site, intronic splice sites, regulatory regions upstream or downstream of the gene, or may introduce premature stop codons or alter mRNA stability.
• Combined or rare mutations: these include delta-beta-thalassemia, deletions involving both the delta and beta genes, structural variants such as HbE, Hb Lepore and Hb Constant Spring, or conditions in which thalassemia coexists with other hemoglobinopathies, for example the combination of a beta-thalassemia variant and HbS, producing HbS/β-thalassemia.

The final result of these genetic abnormalities is a quantitative deficiency of a specific globin chain, producing an imbalance relative to the other chains that are normally synthesized. Already within the erythroid precursor, this imbalance interferes with hemoglobin assembly and causes precipitation of unincorporated free chains, for example excess alpha chains in beta-thalassemia.

The clinical picture depends crucially on the number of affected genes and the type of mutation. In alpha-thalassemias, the spectrum ranges from silent carrier status, inactivation of a single copy, to alpha-thalassemia trait, two inactivated copies, HbH disease, generally three inactivated copies, and Hb Bart syndrome, caused by functional inactivation of all four copies through deletions or, less commonly, nondeletional variants. In beta-thalassemias, the phenotype depends on zygosity, residual beta-globin synthesis and genetic modifiers: trait/minor is generally heterozygous, whereas intermedia and major forms are usually caused by biallelic HBB variants, with severity modulated by the combination of β0, β+ or milder alleles.

Thalassemias are inherited, but the pattern depends on the defect: clinically severe beta-thalassemia is generally biallelic, whereas alpha-thalassemia depends on the number and arrangement of the four HBA copies; rare dominant variants, de novo deletions and modifiers in cis or in trans also exist. Carriers may be asymptomatic or have hematologic abnormalities and can transmit the variant to their offspring. Thalassemias became more frequent in populations where malaria was historically endemic: some heterozygous genotypes confer a selective advantage, mainly by reducing the risk of severe malaria and clinical progression.

In rare cases, coinheritance abnormalities may occur, for example the simultaneous presence of a thalassemia and a structural hemoglobin variant such as HbS, HbC or HbE, producing distinctive and sometimes more severe clinical pictures depending on the interaction between the different molecular defects.

Finally, the increasing incidence of compound forms, such as coinheritance of beta and delta mutations or rare variants, in multicultural and migrant populations creates new diagnostic and therapeutic challenges, often requiring second-level genetic testing and specialist hematogenetic counseling.

Pathogenesis and Pathophysiology

To understand the pathogenetic mechanisms of thalassemias, it is essential to recall that under physiologic conditions hemoglobin is a tetrameric molecule assembled from two pairs of globin chains, alpha and non-alpha, meaning beta, gamma or delta, and four heme groups, each capable of reversibly binding one oxygen molecule. This modular structure and the precise balance of chain production ensure formation of stable hemoglobin that transports and releases oxygen efficiently to tissues. Variations in the ratio among chains, tightly regulated during embryonic, fetal and adult life, reflect adaptation to different oxygen-affinity requirements at different stages of development.

In thalassemias, a genetic mutation causes reduced or absent synthesis of a particular globin chain, altering the quantitative ratio between alpha and non-alpha chains. In beta-thalassemia, unpaired alpha chains accumulate and precipitate in erythroid precursors, generating oxidative stress and apoptosis. In alpha-thalassemia, excess gamma chains during fetal life or beta chains after birth form abnormal tetramers, respectively Hb Bart and HbH, with different functional and stability properties.

In severe forms, particularly beta-thalassemia major, ineffective erythropoiesis may be profound: a large proportion of erythroid precursors die in the marrow before maturation and circulating erythrocytes are more susceptible to hemolysis. The result is chronic anemia whose severity is proportional to the globin defect; in carriers and minor forms, erythropoiesis may instead be only mildly altered or clinically silent.

In severe forms that are not adequately compensated, chronic anemia stimulates increased erythropoietin secretion. Persistent stimulation may cause erythroid hyperplasia and marrow expansion, with cortical thinning and craniofacial deformities; it may also activate extramedullary hematopoiesis in the spleen, liver, or paraspinal and mediastinal sites, causing organomegaly or compressive complications.

In intermediate or major forms and in transfused patients, another central pathogenetic factor is iron overload. Ineffective erythropoiesis may suppress hepcidin, particularly through erythroferrone, increasing intestinal absorption; in transfusion-dependent patients, this is compounded by iron introduced through transfused red blood cells. Excess iron may deposit in the liver, heart, pancreas and endocrine glands, causing fibrosis, cellular toxicity and organ injury.

Red blood cell morphologic abnormalities vary according to the form and severity of thalassemia: microcytosis and hypochromia are common, whereas marked anisopoikilocytosis, target cells and circulating erythroblasts are mainly findings of the more clinically significant forms; in heterozygous carriers the abnormalities are generally milder and erythroblasts are usually absent.

Finally, the severity of the clinical presentation and systemic complications depends on the degree of ineffective erythropoiesis and how early iron overload develops. The most severe forms present early: alpha-thalassemia hydrops fetalis prenatally and beta-thalassemia major during the first months of life, with severe anemia, jaundice, splenomegaly, growth delay and skeletal deformities. Intermediate forms may develop late complications, whereas minor forms and traits generally remain asymptomatic or limited to mild hematologic abnormalities.

In summary, thalassemia pathogenesis reflects convergence of several mechanisms:

• Imbalanced globin-chain synthesis, with accumulation of free chains or formation of abnormal tetramers depending on the defect, and possible oxidative injury
• Ineffective erythropoiesis and chronic anemia of variable severity in clinically significant forms, aggravated by peripheral hemolysis
• Marrow expansion and activation of extramedullary hematopoiesis in severe forms that are not adequately compensated
• Progressive iron overload and organ toxicity in intermediate, major or transfused forms

These processes, which begin at the level of the erythroid cell, profoundly affect hematologic physiology and the clinical course of patients with thalassemia.

Classification and Epidemiology

Thalassemias are an extremely heterogeneous group of inherited hemoglobinopathies whose classification reflects the complexity of globin genetics and the diversity of clinical presentations. In practice, classification is based on three principal parameters: the globin chain affected, the number of genes involved and the severity of the clinical phenotype. These criteria distinguish the main forms of thalassemia and guide diagnostic and therapeutic management.

According to the deficient globin chain, the principal categories are:

• Beta-thalassemias: these result from mutations in the beta-globin gene (HBB) on chromosome 11, causing reduced (β+) or absent (β0) beta-chain synthesis. Beta-globin deficiency creates a relative excess of alpha chains responsible for the specific pathogenesis.
• Alpha-thalassemias: these are caused by deletions or, less commonly, point mutations in the alpha-globin genes (HBA1, HBA2) on chromosome 16. The clinical picture depends on the number of alpha genes involved, from one to four, and the severity of the resulting deficiency.
• Rare thalassemias and combined forms: these include defects in synthesis of other globin chains (gamma, delta), thalassemias with structural variants (HbE, Hb Lepore, Hb Constant Spring and others), or combinations of thalassemia with other hemoglobinopathies, for example HbS/β-thalassemia, delta-beta-thalassemia and HbE/β-thalassemia.

From a phenotypic standpoint, thalassemias are further classified according to the severity of the clinical presentation:

• Thalassemia major: a severe form characterized by severe anemia from the first months of life, need for regular transfusions, marked marrow expansion, growth delay and development of complications from iron overload.
• Thalassemia intermedia: later onset and a less severe clinical picture; patients may maintain hemoglobin levels sufficient to avoid regular transfusions but remain at risk of chronic complications, particularly skeletal, endocrine, cardiovascular and infectious complications.
• Thalassemia minor (or healthy carrier): a heterozygous carrier of the mutation, generally asymptomatic, with microcytosis and hypochromia often found incidentally on a complete blood count. Although clinically silent, this condition is extremely important for prevention of severe forms and genetic counseling.

The major/intermedia/minor classification is historical and descriptive; for clinically significant forms, modern management distinguishes mainly TDT, transfusion-dependent thalassemia, and NTDT, non-transfusion-dependent thalassemia, categories that do not correspond perfectly to the traditional nomenclature.

In alpha-thalassemias, classification is instead based on the number of functional alpha genes:

• Loss of one gene: silent carrier, completely asymptomatic.
• Loss of two genes: alpha-thalassemia trait, with microcytosis and absent or mild anemia.
• Loss of three genes: HbH disease, with hemolytic anemia of variable severity.
• Loss of all four genes: hydrops fetalis due to Hb Bart's, a condition almost invariably fatal without intrauterine treatment and specialist perinatal care.

The molecular classification of mutations (β0, β+, combinations of deletions and mutations) and the presence of structural hemoglobin variants now allow highly accurate definition of individual clinical risk and prevention strategies, particularly in high-prevalence populations or families with a history of disease.

From an epidemiologic perspective, thalassemias are among the most common genetic diseases worldwide. The global burden is high and includes many births each year with clinically significant forms, concentrated mainly in regions with a high carrier frequency. Geographic distribution follows a natural-selection pattern: prevalence is highest in areas historically endemic for malaria, where some heterozygous genotypes mainly reduced the risk of severe malaria and promoted transmission of the variants to subsequent generations. The Mediterranean basin (Italy, Greece, Cyprus and North Africa), the Middle East, India, Southeast Asia, southern China and some regions of sub-Saharan Africa have the highest carrier rates and numbers of clinical cases.

Migration over recent decades has resulted in a “globalization” of thalassemias, making diagnosis and prevention a healthcare challenge even in countries where they were previously nonendemic, such as northern Europe, North America and Australia. In many of these areas, carrier diagnosis and genetic counseling are now integral parts of public health programs.

Recognition of the extraordinary genetic and phenotypic heterogeneity of thalassemias is now fundamental not only for individual diagnosis, but also for screening strategies, development of new treatments and planning of public health interventions worldwide.

Clinical Manifestations

The clinical manifestations of thalassemias reflect the extraordinary heterogeneity of this group of hemoglobinopathies and depend on multiple factors: the type of globin chain involved, the number of affected genes, the nature of the mutations, age at onset and the presence of complications or comorbidities. In general, the clinical picture is dominated by the consequences of chronic anemia, ineffective erythropoiesis, hemolysis and progressive iron overload, but the intensity and combination of symptoms vary greatly among forms and even among individual patients.

In beta-thalassemia major, symptoms typically appear between 6 and 24 months of age, when fetal hemoglobin (HbF) is progressively replaced by adult hemoglobin and beta-chain deficiency becomes manifest. Affected children develop progressive pallor, mild jaundice, growth delay and marked fatigue, often associated with poor feeding and poor weight gain. Severe anemia may cause tachycardia, exertional dyspnea, palpitations and, in more advanced cases, signs of heart failure and multiorgan failure.

One of the most characteristic clinical features of severe forms is the development of skeletal deformities caused by massive marrow erythroid hyperplasia and expansion of craniofacial bones: patients may develop frontal bossing, maxillary hypertrophy, flattening of the nasal bridge and increased interorbital distance, producing the typical “thalassemic facies.” Long bones are also thinned and at risk of spontaneous fracture. In parallel, splenomegaly and hepatomegaly are almost always present because of both hemolysis and activation of extramedullary hematopoiesis. In untreated cases, splenomegaly may become massive, with risks of splenic infarction, hypersplenism and hemorrhagic or infectious complications.

Chronic hemolysis contributes to persistently elevated indirect bilirubin, promoting scleral and cutaneous jaundice, generally mild, gallstones and, in more advanced cases, further worsening of anemia through accelerated red blood cell destruction.

A characteristic and clinically important complication of transfusion-dependent thalassemias is progressive iron overload, which over time leads to multisystem complications:

• Heart: dilated cardiomyopathy, arrhythmias and congestive heart failure.
• Liver: chronic liver disease, cirrhosis and increased risk of hepatocellular carcinoma.
• Pancreas: diabetes mellitus secondary to pancreatic hemosiderosis.
• Endocrine glands: hypogonadism, hypothyroidism and adrenal insufficiency.
• Musculoskeletal system: osteopenia, osteoporosis, skeletal deformities and delayed bone age.

These complications develop progressively as iron accumulates through increased intestinal absorption in nontransfused cases and transfusional loading in major and some intermediate forms.

In intermediate forms, manifestations are subtler and onset may be delayed until adolescence or adulthood. Patients may maintain relatively normal activity but progressively develop splenomegaly, moderate chronic anemia, mild jaundice, gallstones and skeletal abnormalities. Iron-overload complications develop more slowly but remain possible, especially with even occasional transfusions or dysregulated iron absorption.

In minor forms or healthy carriers, thalassemia is usually asymptomatic. The only finding may be microcytosis and hypochromia detected on a routine complete blood count, without significant anemia. Under hematopoietic stress, such as pregnancy, infection or blood loss, a modest reduction in hemoglobin may occur. From epidemiologic and preventive perspectives, these individuals are fundamental because, if unidentified, they may transmit severe mutations to their offspring.

In addition to the principal manifestations, thalassemias are frequently associated with:

• Increased infectious risk, particularly in patients who have undergone splenectomy, have functional asplenia, iron overload or venous devices.
• Coagulation abnormalities and thrombotic tendency, more evident in intermediate forms and nontransfused adults.
• Pulmonary complications, including pulmonary hypertension, especially in chronic forms.
• Impaired growth and pubertal development due to endocrine and skeletal involvement.

The overall picture may be further complicated by coexisting hemoglobin variants, modifier mutations, adherence to transfusion and chelation therapy, and the patient’s socioeconomic and nutritional circumstances.

It should be emphasized that the course and severity of manifestations are strongly influenced by early diagnosis, treatment adherence and quality of multidisciplinary follow-up. In specialist centers, survival and quality of life for patients with thalassemia major have improved substantially but remain variable and dependent on complications and continuous access to care, whereas in resource-limited areas the disease still carries very high morbidity and mortality.

Investigations and Diagnosis

Diagnosis of thalassemia requires an integrated pathway beginning with clinical suspicion, based on personal and family history and laboratory findings, and proceeding through sequential hematologic, biochemical and molecular tests. The main objective is not only to identify the disease but to define its form, severity and genetic characteristics accurately, which is essential for prognosis, treatment planning and family counseling.

Clinical suspicion usually arises in the presence of unexplained hypochromic microcytic anemia, after more common causes such as iron deficiency have been considered, especially in children or young adults, individuals from high-prevalence regions, or those with a family history of anemia, splenomegaly or deaths from hydrops fetalis. Skeletal abnormalities, splenomegaly or signs of iron overload in nontransfused individuals also suggest thalassemia.

The first step in the diagnostic workup is a complete blood count and peripheral blood smear. Microcytosis, reflected by a reduced MCV, hypochromia, reflected by a reduced MCH, an elevated red blood cell count with reduced hemoglobin, and typical anisopoikilocytosis strongly support a diagnosis of thalassemia and help distinguish it from classic iron-deficiency anemia, in which both red blood cell count and hemoglobin are usually reduced in parallel. The peripheral smear may show target cells, poikilocytosis, microcytes and circulating erythroblasts.

A fundamental component of the differential diagnosis is assessment of iron stores: in thalassemia, serum iron, ferritin and transferrin saturation are generally normal or increased, whereas they are reduced in iron deficiency. Excluding true iron deficiency is a key step before proceeding with a diagnosis of thalassemia.

The second diagnostic step is quantitative analysis of hemoglobin fractions by electrophoresis or HPLC, high-performance liquid chromatography. This examination can identify specific abnormalities:

• Increased HbA2, typically above 3.5%, in beta-thalassemia trait; in biallelic major or intermedia forms, the HbA2 proportion is variable according to genotype and the overall hemoglobin profile.
• Increased HbF in children and, to varying degrees, in major forms or some intermediate variants.
• Presence of abnormal hemoglobins, including HbE, Hb Lepore, Hb Constant Spring, Hb Bart’s and HbH, suggesting rare forms or compound syndromes.

It should be remembered that in alpha-thalassemias, changes in hemoglobin fractions may be modest or absent in minor forms; suspicion is based on red blood cell indices, morphology and clinical context, whereas definition of the specific alpha-thalassemia and genetic configuration requires molecular analysis. In more severe forms, HbH inclusions, visible with supravital stains, or Hb Bart’s in the newborn may be present.

A definitive diagnosis and classification of thalassemia are now obtained through genetic testing, which can accurately identify the responsible abnormalities, including deletions, point mutations and rare combinations. Molecular testing by PCR, direct sequencing or MLPA is indispensable for genetic counseling, prenatal diagnosis and prevention of severe forms. In some complex cases, including suspected coinheritance of multiple mutations, atypical phenotypes or nonclassical thalassemias, genetic analysis is the only method capable of clarifying the diagnosis and guiding family management.

When iron overload or organ complications are present, evaluation includes the iron profile, ferritin, serum iron and transferrin saturation, hepatic, cardiac and endocrine function tests, and advanced imaging, particularly T2* MRI to quantify iron in the liver and heart. Early identification of iron-related complications is crucial to prevent organ injury and optimize chelation therapy.

When extramedullary hematopoiesis or paraspinal masses are suspected, ultrasonography, CT or magnetic resonance imaging may be indicated. Skeletal assessment using radiography and densitometry helps evaluate osteopenia, deformities and fracture risk.

Diagnosis of thalassemia minor and distinction from silent-carrier status are often incidental, occurring during premarital screening, pregnancy, blood donation or preoperative evaluation. Carrier identification and genetic counseling are now fundamental pillars of prevention strategies in at-risk populations.

In summary, diagnosis of thalassemia follows a logical sequence:

• Clinical and laboratory suspicion in unexplained hypochromic microcytic anemia.
• Exclusion of iron deficiency through serum iron and ferritin testing.
• Characterization of hemoglobin fractions by electrophoresis/HPLC.
• Genetic analysis for molecular definition and family counseling.
• Screening for organ complications and risk stratification.

This pathway enables not only early diagnosis of clinically relevant forms but also implementation of prevention programs and personalized treatment.

Treatment and Prognosis

Management of thalassemias is one of the most complex challenges in modern hematology and requires a multidisciplinary approach integrating treatment of anemia, prevention and management of complications, care of iron overload, and psychological, social and genetic support for patients and families. Treatment varies according to disease severity, patient age, available resources and the presence of comorbidities or organ complications.

Transfusion therapy

In transfusion-dependent forms, historically comprising mainly beta-thalassemia major and some intermediate phenotypes, periodic transfusion of packed red blood cells is the cornerstone of management. The objective is to maintain hemoglobin levels sufficient to prevent clinical manifestations of anemia and suppress marrow hyperplasia and extramedullary hematopoiesis. For most patients with transfusion-dependent thalassemia, the pretransfusion target is 9.5–10.5 g/dL; it may be increased to 10–11 g/dL in the presence of cardiac disease or pulmonary hypertension, clinically significant extramedullary hematopoiesis or inadequate marrow suppression, whereas during pregnancy the target is approximately 10 g/dL.
Before the first transfusion, extended red blood cell typing should be performed at least for Rh C/c/D/E/e and Kell; subsequent transfusions must use units prophylactically matched at least for C, c, E, e and K, in addition to ABO/RhD, to reduce the risk of alloimmunization and transfusion reactions. Careful monitoring of iron balance and acute or chronic adverse events is essential.

Iron chelation therapy

Because the human body has no physiologic system for eliminating excess iron, repeated administration of blood inevitably leads to iron overload, or hemosiderosis. Chelation therapy is therefore essential for survival and quality of life in transfusion-dependent patients. The principal chelators currently used are:

• Deferoxamine (DFO): administered subcutaneously or intravenously, it requires prolonged infusions and may be associated with poor adherence in children and young adults.
• Deferiprone (DFP): an oral chelator particularly effective in removing cardiac iron, associated with risks of neutropenia and agranulocytosis.
• Deferasirox (DFX): a widely used oral chelator that improves quality of life and requires monitoring of renal and hepatic function.

The choice of chelator, dose and duration of therapy is individualized according to ferritin levels, organ iron burden, monitored by cardiac and hepatic T2* MRI, individual tolerability and comorbidities.

Splenectomy

Surgical removal of the spleen is indicated only in selected cases when splenomegaly causes refractory hypersplenism, with severe cytopenia, or excessively increases transfusion requirements. The risk of fulminant infection with encapsulated organisms, Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis, must always be considered; patients therefore require vaccination and long-term antibiotic prophylaxis.

Supportive treatment and prevention of complications

Comprehensive care of patients with thalassemia also includes prevention and management of endocrine complications, with monitoring of growth, pubertal, thyroid, adrenal and glycemic function, bone health, including vitamin D, calcium and bone densitometry, and cardiac, hepatic and renal function. Bisphosphonates or other bone-protective drugs may be indicated in osteopenia. Particular attention is given to nutritional support, infection prevention and promotion of physical activity appropriate to the patient’s health status.

Innovative treatments and transplantation

In recent years, gene therapy, editing strategies that reactivate fetal hemoglobin, erythroid maturation agents such as luspatercept, and metabolic modulators have profoundly changed the therapeutic landscape of thalassemias. In the European Union, mitapivat is authorized in adults for anemia associated with alpha- or beta-thalassemia, both transfusion-dependent and non-transfusion-dependent. Access to the different therapies remains limited to specific regulatory indications and requires assessment at specialist centers.
Hematopoietic stem cell transplantation (HSCT) is an established potentially curative option for thalassemia major; gene or gene-editing therapies are also authorized for selected indications in some jurisdictions. The success of the procedure depends on several factors, including patient age, donor compatibility, clinical condition and absence of organ complications. Transplantation nevertheless carries significant risks, including rejection, graft-versus-host disease and severe infections, and should be reserved for selected cases according to international guidelines.

Prognosis

The prognosis of thalassemias has improved substantially through advances in early diagnosis, organization of transfusion care and availability of effective chelators. In referral centers, life expectancy in patients with thalassemia major has increased substantially but remains reduced on average and strongly dependent on prevention and management of organ complications. Factors affecting prognosis include:

• Early diagnosis and initiation of treatment
• Quality and continuity of transfusion and chelation therapy
• Systematic monitoring of iron overload and complications
• Access to advanced therapies, including transplantation, gene therapy and innovative drugs
• Patient adherence to multidisciplinary follow-up

The prognosis is excellent in minor forms and carriers, apart from rare complications under conditions of physiologic stress or pregnancy. Intermediate forms have widely variable outcomes depending on disease course and the presence of modifier mutations.

In conclusion, treatment of thalassemias is not standardized but requires individualized therapy and comprehensive care directed not only toward survival but also toward quality of life and social integration.
Future prospects, driven by biotechnology, gene therapy and prevention strategies, point toward an increasing possibility of definitive cure and prevention of the most severe forms, particularly in high-prevalence countries.

Complications

Complications of thalassemias are the principal determinants of morbidity and mortality in the natural history of disease, especially in major and inadequately treated intermediate forms. They result from the direct consequences of chronic anemia and ineffective erythropoiesis, progressive tissue iron accumulation, transfusion therapy and associated immunologic abnormalities.

Complications of iron overload

In forms of thalassemia with clinically significant iron overload, particularly transfusion-dependent thalassemia and some non-transfusion-dependent forms, excess iron is a major cause of organ injury. The tissues most frequently affected include:

• Heart: myocardial iron deposition causes dilated cardiomyopathy, arrhythmias, congestive heart failure and, in untreated cases, sudden death. Cardiac injury due to hemosiderosis was historically one of the principal causes of death; in settings with MRI monitoring and adequate chelation, cardiac mortality has fallen significantly, although it remains a serious complication.
• Liver: hepatic hemosiderosis, fibrosis and, over time, cirrhosis develop, with increased risk of hepatocellular carcinoma, particularly in the presence of viral coinfections (HBV, HCV).
• Pancreas: iron damages pancreatic beta cells, promoting secondary diabetes mellitus and glucose intolerance.
• Endocrine glands: iron deposition in the pituitary, thyroid, adrenal and gonadal glands causes hypogonadism, amenorrhea, delayed puberty, hypothyroidism, adrenal insufficiency and infertility.
• Musculoskeletal system: iron toxicity is associated with osteopenia, osteoporosis, pathologic fractures, skeletal deformities, growth delay and impaired bone mineralization.

Complications related to chronic anemia and ineffective erythropoiesis

Severe anemia and persistent compensatory erythropoietic demand cause a range of systemic manifestations and complications:

• Skeletal abnormalities: marrow hyperplasia, expansion of craniofacial bones producing “thalassemic facies,” thinning of long bones and increased risk of fractures and deformities.
• Growth and pubertal delay: common in children and adolescents and aggravated by endocrine and nutritional complications.
• Extramedullary hematopoiesis: development of paraspinal, mediastinal or abdominal erythropoietic masses that may cause neurologic or respiratory compression.
• Massive splenomegaly and hypersplenism: with multiple cytopenias, splenic hyperfunction and risk of spontaneous rupture or splenic infarction.

Infectious complications

Patients with clinically significant thalassemia may have increased susceptibility to infections, especially in the presence of splenectomy or functional asplenia, iron overload, venous devices, repeated transfusions or comorbidities. Infections with encapsulated organisms, including pneumococcus, meningococcus and Haemophilus influenzae, and blood-borne viruses, including HBV, HCV, HIV and Parvovirus B19, represent a significant risk of morbidity and mortality. In particular, fulminant sepsis and malaria in endemic areas may be lethal in patients who have not received appropriate prophylaxis.

Cardiovascular and thromboembolic complications

In addition to myocardial iron injury, thalassemias are associated with a higher incidence of pulmonary hypertension, arrhythmias and thromboembolic events, particularly in intermediate forms and after splenectomy, attributed to hypercoagulability, red blood cell membrane abnormalities and blood stasis in the pulmonary and systemic circulations.

Hepatobiliary complications

Persistent hemolysis and increased production of indirect bilirubin cause gallstones (pigment stones) and, over time, a risk of cholecystitis and biliary complications.

Neoplastic complications

The risk of liver tumors, particularly hepatocellular carcinoma, related to hemosiderosis and chronic viral infections, is significantly increased in transfusion-dependent patients, especially in adulthood.

Psychosocial complications

The chronic nature of the disease, the need for invasive treatments and awareness of the risk of organ complications have a major impact on quality of life and psychological adaptation of patients and their families. Depression, anxiety, adjustment disorders and difficulties with school, work and social integration are common, especially in countries with limited resources and specialist support.

Treatment-related complications

Transfusions carry a non-negligible risk of alloimmunization, formation of anti-red-cell antibodies, acute and chronic transfusion reactions, transmission of infectious agents and, in rare cases, acute volume overload or heart failure. Chelation therapy may also cause adverse effects, including nephropathy, cytopenias, gastrointestinal disorders, and ocular and auditory toxicity, requiring careful monitoring and individualized treatment adjustments.

Rare complications

In some intermediate or atypical forms, noncirrhotic portal hypertension, lower-limb ulcers, renal dysfunction, neurologic complications secondary to erythropoietic masses and aplastic crises due to Parvovirus B19 may occur.

The overall burden of complications, often simultaneous or interdependent, determines the individual risk profile and quality of life of patients with thalassemia. Their prevention, early identification and integrated management are the core objectives of follow-up in specialist centers.

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