Category: guide

Thalassemia is a hereditary blood disorder that all medical students hear about early in their academic careers. Still, its concept becomes clearer when various causal factors, such as genetic mutations and haemoglobin synthesis, are linked to clinical outcomes. 

From subtle laboratory findings to features such as the thalassemia face, this disorder illustrates how a defect in just one gene can alter the entire physiology of blood. Having a strong grasp of this topic will make your preparation better for NEET PG while giving you a newfound perspective on the precision of human biology.

Keep reading for a detailed analysis.

What is Thalassemia?

Thalassemia is an inherited blood disorder in which the body makes less haemoglobin due to faulty alpha or beta globin chains, leading to fragile red blood cells and long-term anaemia. The condition is passed on when both parents carry the gene.

Thalassemia is a genetic blood disease characterised by reduced or absent synthesis of alpha or beta globin chains. These chains make up the haemoglobin molecule, so their underproduction results in defective haemoglobin formation.

Red blood cells become both fragile (easily destroyed) and are produced in reduced numbers. This consequently causes an imbalance in the production of chronic hemolytic anaemia, together with long-term systemic strain.

The type of thalassemia depends on which globin chain gene is affected:

1. Alpha Thalassemia

• It is caused by deletions in one or more of the four alpha-globin genes͏ 
• The greater the number of deletions, the more severe it is
• It runs a range from a silent carrier state to hydrops fetalis­, which is typically lethal

2. Beta Thalassemia

• Point mutations in the beta-globin gene cause it
• Leads to either absent production (β⁰) or reduced production (β⁺)
• Severity varies from an asymptomatic trait to severe thalassemia major

The disease is autosomal recessive, meaning both parents must carry the gene for a child to have severe disease. Here’s a table comparing the Alpha Thalassemia and Beta Thalassemia side by side:

What are the Causes of Thalassemia?

Genetic changes are the primary cause of thalassemia, which manifests differently in alpha-gene deletions and beta-gene point mutations. These molecular defects play a crucial role in determining the severity and clinical manifestations of this condition.

Thalassemia results from acquired gene mutations that reduce globin chain production. While both types ultimately result in anaemia, the underlying genetic mechanisms vary greatly.

Listed below are the common causes of Thalassemia:

1. Mutations of Genes encoding Hemoglobin

The fundamental aetiology is based on mutations or deletions in the genes that normally encode the alpha or beta globin chains of haemoglobin. Defective chains impair the formation of haemoglobin and eventually result in ineffective erythropoiesis and hemolysis.

2. Alpha Globin Gene Deletions

Large deletions that remove or inactivate alpha-globin genes typically cause alpha thalassemia.

• One Gene Deletion: Silent carrier and shows no symptoms
• Two Gene Deletions: Alpha thalassemia trait, which causes mild anaemia
• Three Gene Deletions: HbH disease, which causes moderate to severe anaemia
• Four Gene Deletions: Hydrops fetalis, which is typically incompatible with life

3. Beta Globin Gene Point Mutations

Beta thalassemia arises mainly from point mutations rather than deletions. These mutations affect:

• Promoter regions
• Coding regions
• RNA splicing sites

Based on the mutation, beta chain production may be partially reduced (β⁺) or completely absent (β⁰).

4. Imbalance of Globin Chains

The key pathogenic feature is that the body synthesises an unbalanced globin chain. For instance, excess alpha chains in beta thalassemia, or excess beta chains in alpha thalassemia. These unstable chains precipitate inside RBCs, damaging their membrane and leading to hemolysis.

What are the risk factors of Thalassemia?

Several factors contribute to the increased likelihood of thalassemia inheritance, including family histories of thalassemia, ethnic predominance of certain groups that frequently carry thalassemia genes, consanguinity, the inaccessibility of screening technologies, and limited awareness.

Since thalassemia is a genetic condition, inheritance and the geographic distribution of populations are major risk factors. Let’s see each risk factor of Thalassemia in detail:

1. Family history of Thalassemia

If both parents pass on the inherited mutation of thalassemia, their child’s chances of:

• Developing thalassemia major is 25%
• Being a carrier is 50%
• Inheriting neither of their parents’ mutations is 25%

The mentioned pattern of inheritance indicates the need for premarital and preconception testing.

2. High-Risk Ethnic Groups

Thalassemia occurs more frequently in regions where malaria is widely prevalent. Malaria carriers developed partial immunity to severe malaria, allowing the persistence of thalassemia in their genomes. These regions are:

• Countries surrounding the Mediterranean Sea (Italy, Greece, Cyprus)
• Arab countries in the Middle East
• Southern Asian countries (India, Pakistan, Bangladesh)
• Southeast Asian countries (Thailand, Malaysia, Vietnam)

Elevated carrier rates exceeding 10% for the Beta Thalassemia Trait exist within certain regions of India.

3. Consanguinity

Marriages between two relatives increase the probability that each partner is a carrier of the same mutation, thereby increasing the likelihood that their children will inherit a severe form of thalassemia.

4. Lack of Screening and Awareness

The inability to test for Thalassemia has increased number of children with Thalassemia major. Regions without established screening programs for thalassemia major have higher rates of undetected carrier couples, thereby increasing the prevalence of thalassemia major.

What are the Symptoms of Thalassemia?

There are differences in the clinical manifestations of different types of thalassemia. At one end of the continuum, you have asymptomatic individuals. At the other end, there are children with symptoms such as severe anaemia, skeletal deformities, and facial abnormalities from the expansion of the bone marrow.

The clinical and laboratory findings in all patients with thalassemia vary over the course of their lives. Therefore, understanding the broad range of symptoms that can occur is essential for making accurate differential diagnoses.

1. Thalassemia Minor (Trait)

This usually shows no symptoms. However, in the management of individuals who have thalassemia minor (trait), it is important to understand that:

• Mild microcytic anaemia is common.
• Some individuals may report fatigue.
• All aspects of their general health may be normal.

2. Thalassemia Intermedia

Individuals usually develop moderate anaemia but typically do not require regular blood transfusions unless the condition worsens. Thus, these individuals will typically experience:

• Fatigue on exertion.
• Jaundice (yellowing of the skin and sclera).
• Splenomegaly (enlarged spleen).
• Bone Pain from bone marrow expansion, resulting in unnecessary blood transfusions.

3. Thalassemia Major (Cooley’s Anaemia)

Patients with beta-thalassemia major appear healthy at birth but rapidly develop symptoms as they grow. Most commonly, these manifestations include:

• Severe Anemia
• Thalassemia Face
• Enlarged liver and spleen
• Delayed growth and development
• Bone fragility

How is Thalassemia Diagnosed?

Thalassemia is diagnosed using blood counts, peripheral smear findings, haemoglobin electrophoresis, genetic studies, and the NESTROFT test, which serves as a simple and widely used population screening tool.

Diagnosing thalassemia requires determining a pattern in the blood count and confirming the haemoglobin pattern or identifying genetic defects if needed. Routinely starting with blood testing and moving on to molecular testing methods.

Let’s see each of the diagnostic techniques in detail:

1. Complete Blood Count

CBC results typically show:

• Low MCV
• Low MCH
• Normal or high RBC count

A classic indication is that the MCV is lower than expected compared to the degree of anaemia.

2. Peripheral Blood Smear

Peripheral blood smears show:

• Microcytic changes
• Hypochromic changes
• Target cells
• Basophilic stippling
• Anisopoikilocytosis.

These are used to differentiate thalassemia from iron deficiency anaemia.

3. Haemoglobin Electrophoresis/HPLC

The best initial test to confirm the type of thalassemia is Hb electrophoresis/HPLC. It indicates:

• Beta Thalassemic Trait at an elevated HbA2 level
• Beta Thalassemic Major when there is a significantly elevated level of HbF and little to no detectable level of HbA
• Alpha Thalassemia, when the Hb electrophoresis test is generally normal unless HbH or Bart’s is present.

4. Genetic Tests

The use of genetic studies is most beneficial in the following cases:

• Detection of a prenatal diagnosis
• A questionable or atypical case
• Family screening
• Confirmation of alpha thalassemia deletion.

5. NESTROFT Test

The Naked Eye Single Test Tube Osmotic Fragility Test is a widely used screening method for this condition. The following points highlight the advantages of this test as a screening tool:

• By detecting decreased osmotic fragility, the NESTROFT test can be used to identify beta thalassemia trait.
• The appearance of a turbid solution indicates a positive result.
• The test is simple, inexpensive, and is an efficient method for screening a very large population.

Although NESTROFT is not a diagnostic test, it can serve as a handy screening tool in resource-limited areas.

What are the Treatment Options for Thalassemia?

The major treatment strategies for thalassemia explain why patients need transfusions, how iron chelation prevents organ damage, and why bone marrow transplant is currently the only curative method.

Thalassemia treatment focuses on correcting anaemia, preventing iron overload, and improving quality of life. The approach depends on disease severity.

Here are all the treatment options for thalassemia in detail:

1. Lifelong Regular Blood Transfusions

This treatment is required by children with thalassemia major to provide sufficient haemoglobin for growth, to protect against skeletal deformities (dental and bone), and to decrease the risk of extramedullary hematopoiesis.

2. Iron Chelation Therapy

The use of iron chelation therapy prevents iron-related organ damage from chronic erythropoiesis. Lifelong use of chelation therapy is required for transfusion-dependent thalassemia patients.

3. Folate Supplementation

This helps increase the number of red blood cells due to increased demand for folic acid and supports the production of additional red blood cells.

4. Splenectomy

Patients undergo splenectomy in the following situations:

• When the spleen is excessively enlarged
• Transfusion needs have sharply increased
• Cytopenias due to hypersplenism

However, splenectomy is not performed routinely due to the increased risk of infection.

5. Stem Cell or Bone Marrow Transplantation

It is currently the only way to permanently cure thalassemia, with the best outcomes for younger patients (under the age of 5) who have matched donors before the onset of significant iron overload.

What are the Complications of Untreated Thalassemia?

Untreated thalassemia leads to serious long-term complications, including organ damage, bone deformities, growth delays, and heart failure, emphasising the importance of early diagnosis and consistent treatment.

Unmanaged thalassemia can lead to severe complications due to anaemia and iron overload. Let’s see what these complications are:

• Deformities of bones due to marrow expansion
• Growth retardation, as impaired oxygenation influences growth hormone
• Iron overload, which causes heart failure, arrhythmias, cirrhosis, diabetes, and hypothyroidism
• Recurrent infections, particularly post-splenectomy
• Chronic fatigue and poor quality of life
• Gallstones due to chronic hemolysis
• Cardiomyopathy, which is the commonest cause of death in untreated cases

These complications can be significantly minimised with timely treatment.

How to Prevent Thalassemia?

Various strategies for thalassemia prevention, including carrier screening, NESTROFT testing, genetic counselling, and prenatal diagnosis, play an important role in reducing thalassemia incidence, especially in high-risk geographic areas.

Here’s a list of preventive measures involving carrier identification in early life and educating couples about reproductive choices:

1. Carrier Screening

Screening of young adults or couples before marriage is highly effective and reduces the carrier risk of thalassemia. These screening techniques are:

• CBC
• Hemoglobin electrophoresis
• NESTROFT

2. Genetic Counselling

Counselling assists couples in understanding:

• Their risk of carrying the condition.
• Possible outcomes if they are potential carriers.
• Reproductive technologies are available to prevent the inheritance of this condition.

3. Prenatal Diagnosis

This ensures that cases of affected fetuses are detected early. It is done using:

• Chorionic villus sampling
• Amniocentesis
• DNA mutation analysis

4. Public Awareness Programs

Countries like Cyprus and Iran have experienced a decrease in thalassemia incidence due to mandatory premarital screening and public awareness programs.

FAQs about Thalassemia 

1. Can thalassemia be cured?

Yes, but only a stem cell or bone marrow transplant can provide a complete cure. Other supportive therapies help control the symptoms but do not affect the genetic disorder.

2. What is the thalassemia face?

Thalassemia facies refers to facial changes caused by bone marrow overgrowth in the facial bones. Characteristics of this condition are frontal bossing,  maxillary prominence, and a flat nasal bridge.

3. What is the NESTROFT test?

NESTROFT is a simple, low-cost test for screening persons who may carry beta thalassemia by identifying the resistance or fragility of red blood cells to osmosis.

4. Can individuals with thalassemia trait lead normal lives?

Yes, most people with thalassemia trait are healthy with no signs or symptoms, and their lives are normal.

5. Can thalassemia impact pregnancy?

Yes, it can, as pregnant women with thalassemia may experience increased anaemia or iron overload and therefore need careful monitoring and coordinated medical care throughout pregnancy.

Conclusion

Thalassemia represents a genetically transmitted disorder with considerable variability in terms of clinical presentations, ranging from carriers with no visible symptoms to those requiring lifelong management. Early diagnostic and preventive strategies can help reduce the prevalence of this condition.

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