When we think about inherited health conditions, thalassemia stands out as one of the most significant blood disorders affecting millions of people worldwide – including a large number in South Asia. It is not an infection, not an accident, and not something that develops over time. Thalassemia is written into a person’s genetic code from the moment of conception. Understanding its nature – what it is, how it works at the molecular level, and why some people are more severely affected than others – is essential for educators, caregivers, and anyone involved in disability-inclusive environments.
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Thalassemia as an inherited disorder
At its most fundamental level, thalassemia is a genetic blood disorder – one that a person is born with, not one they acquire. The Rights of Persons with Disabilities (RPwD) Act, 2016 formally defines thalassemia as “a group of inherited disorders characterised by reduced or absent amounts of haemoglobin.” This legal recognition under Indian law is significant: the RPwD Act, 2016 expanded the recognized list of disabilities from 7 to 21 conditions, bringing blood disorders like thalassemia, hemophilia, and sickle cell disease under the protection of disability law for the first time.
The disorder is caused by mutations in the genes responsible for producing hemoglobin. These gene mutations are passed from parents to their children at the time of conception, which means the condition is present right from birth – even if symptoms do not appear until weeks or months later. According to research published in StatPearls (NCBI), thalassemia is caused either by a genetic mutation or by a deletion of certain key gene fragments, and at least one parent must be a carrier for the condition to be passed on.
The role of hemoglobin
To understand why thalassemia has such a wide impact on the body, it helps to understand what hemoglobin actually does. Hemoglobin is the protein inside red blood cells that is responsible for carrying oxygen – picking it up in the lungs and transporting it to tissues and organs throughout the body. It is, essentially, the body’s oxygen delivery system.
Approximately 98% of all oxygen transported in the blood is bound to hemoglobin, with only 2% dissolved directly in plasma. This makes hemoglobin not just important but absolutely critical for sustaining life and energy. Every cell in the body – from the brain to the muscles – depends on this oxygen delivery to generate energy and function properly.
In thalassemia, the body either produces defective hemoglobin or insufficient quantities of healthy hemoglobin, leading to fewer functional red blood cells. The direct consequence is that the body’s cells receive less oxygen than they need. This shortage of hemoglobin reduces oxygen levels in the body, causing the characteristic fatigue, weakness, and pale skin associated with anemia – and in severe cases, affecting growth, development, and overall organ health.
Structure of hemoglobin and where it goes wrong
Hemoglobin’s structure is what makes it both powerful and vulnerable to genetic errors. It is a protein made up of four subunits: two alpha subunits and two beta subunits, each surrounding a central heme group that contains iron and binds one oxygen molecule – allowing each hemoglobin molecule to carry up to four oxygen molecules at a time.
Each of these protein chains – the alpha chains and the beta chains – is produced according to instructions encoded in specific genes. Alpha globin is coded by four genes (two on each copy of chromosome 16), while beta globin is coded by two genes (one from each parent). A person inherits half of each set from their mother and the other half from their father.
When any of these genes is missing, deleted, or mutated, the affected chain cannot be produced in the right quantity or with the right structure. If the body does not produce sufficient amounts of either of these proteins, red blood cells do not form correctly and cannot carry sufficient oxygen, resulting in anemia that begins in early childhood and persists throughout life.
Types of thalassemia: alpha and beta
Thalassemia is classified based on which globin chain is affected by the genetic defect. The two main categories are alpha thalassemia and beta thalassemia, and their severity varies considerably depending on how many genes are affected.
Alpha thalassemia
Alpha thalassemia occurs when one or more of the four alpha-globin genes are missing or damaged. The severity and type of anemia depends on how many genes are affected. With just one faulty gene, a person is a silent carrier and shows no symptoms at all. Two faulty genes result in mild anemia. Three missing genes – a condition called Hemoglobin H disease – leads to moderate to severe anemia that may require blood transfusions. When all four alpha genes are absent, the condition is almost always fatal before or shortly after birth, a severe outcome known as alpha thalassemia major or hydrops fetalis.
The alpha-globin chains are encoded by two closely linked genes, HBA1 and HBA2, on chromosome 16, and in a person with two copies on each chromosome, a total of four loci encode the alpha chain – two inherited from the mother and two from the father. This is why there are four possible levels of severity in alpha thalassemia.
Beta thalassemia
Beta thalassemia results from mutations in the genes that produce beta-globin chains. Unlike alpha thalassemia, which is typically caused by gene deletion, beta thalassemia is caused by an alteration in the DNA – a point mutation rather than a deletion. Since there are only two beta-globin genes (one from each parent), the inheritance pattern is somewhat simpler to follow.
Mutations in the HBB gene – which provides instructions for making beta-globin – either prevent the production of any beta-globin at all (called beta-zero thalassemia) or allow some beta-globin to be made but in reduced amounts (called beta-plus thalassemia). If a person inherits one altered gene, they typically have mild symptoms (thalassemia minor). If both genes are altered, the outcome is either thalassemia intermedia (moderate severity) or thalassemia major (also called Cooley’s anemia), which is the most severe form and requires lifelong, frequent blood transfusions.
Why the gene imbalance matters
A key reason thalassemia causes harm beyond just a reduction in hemoglobin is the imbalance between alpha and beta chains. When one type of chain is produced in insufficient quantities, the other accumulates in excess. These unpaired chains are unstable and can damage red blood cell membranes, leading to the premature destruction of red blood cells – a process called hemolysis. In beta thalassemia, the excess unpaired alpha-globin chains aggregate and form precipitates that damage red cell membranes, resulting in intravascular hemolysis and premature death of red blood cell precursors – disrupting the entire process of red blood cell production.
This is why the effects of thalassemia extend well beyond tiredness. Untreated or severe thalassemia can affect growth and development in children, delay puberty, cause bone abnormalities, and lead to organ damage over time. The condition does not just reduce energy – it fundamentally disrupts the body’s ability to sustain its own systems.
Who is at risk and why it matters
Thalassemia occurs most often among people of South Asian, Italian, Greek, Middle Eastern, and African descent. In India particularly, thalassemia is a significant public health concern, with a large number of children born with thalassemia major each year. Beta thalassemia occurs most frequently in people from Mediterranean countries, North Africa, the Middle East, India, Central Asia, and Southeast Asia.
Because thalassemia is caused by inherited gene mutations, there is no way to prevent it. However, carriers who are unaware of their status can unknowingly pass the condition on to their children. Genetic counseling and carrier screening are therefore essential – especially for couples planning to have children in populations where the condition is more prevalent. Early identification allows families to make informed decisions and ensures affected children receive timely medical care.
What do you think? Given that thalassemia is a condition present from birth yet may go undetected for months, how can schools and communities better support early identification and inclusion of children living with this condition? And considering that both parents must be carriers for a child to develop the more severe forms of thalassemia, what role should genetic counseling play in public health education in high-prevalence regions like South Asia?
References
- https://www.disabilityrightsindia.com/2017/04/what-21-disabilities-covered-in-rights.html
- https://idronline.org/article/rights/a-primer-on-indias-disability-law/
- https://www.ncbi.nlm.nih.gov/books/NBK545151/
- https://my.clevelandclinic.org/health/body/21691-function-of-red-blood-cells
- https://www.ncbi.nlm.nih.gov/books/NBK538336/
- https://medlineplus.gov/genetics/condition/beta-thalassemia/
- https://courses.lumenlearning.com/wm-biology2/chapter/transport-of-oxygen-in-the-blood/
- https://www.hopkinsmedicine.org/health/conditions-and-diseases/alpha-thalassemia
- https://en.wikipedia.org/wiki/Alpha-thalassemia
- https://www.mayoclinic.org/diseases-conditions/thalassemia/symptoms-causes/syc-20354995
- https://www.hopkinsmedicine.org/health/conditions-and-diseases/beta-thalassemia
- https://www.nhlbi.nih.gov/health/thalassemia/causes
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