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THALASSAEMIA. Konstantinidou Eleni Siligardou Mikela-Rafaella. THALASSAEMIA. The thalassaemias are a group of inherited hematological disorders caused by defects in the synthesis of one or more of the hemoglobin ( Hb ) chains.

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The thalassaemias are a group of inherited hematological disorders caused by defects in the synthesis of one or more of the hemoglobin (Hb) chains.

β-Thalassaemia is caused by reduced or absent synthesis of ß-globin chains.

α-Thalassaemia is caused by reduced or absent synthesis of α-globin chains. Globin-chain imbalances cause hemolysis and impair erythropoiesis.

Globally, an estimated 15 million people have thalassaemia



  • Thalassaemia affects men and women equally and occurs in approximately 4.4 of every 10,000 live births.
  • α-Thalassaemia is most common in individuals of African and Southeast Asian descent, while
  • β-thalassaemia is most common in individuals of Mediterranean, African, and Southeast Asian descent.
  • About 5% of the world's population has a globin variant, but only 1.7% has α- or β-thalassaemia trait.
  • Thalassaemia trait affects 5-30% of people in these ethnic groups.
  • 15% of the people in Greece are carriers of “T”.
  • The prevalence of β-thalassaemia is highest in areas where malaria is (or was) endemic.
  • Similar to β-thalassaemia, α-thalassaemia is prevalent in tropical and subtropical regions, where malaria was or still is endemic.
  • It is thought that carriers of hemoglobinopathies have a degree of protection against malaria, although the mechanism underlying this protection is unknown.
  • Scientists think that this disorder is going to have a major effect on the world in the near future.
  • This disorder may be given to offspring when the parents both have the heterozygous genotype.

Hemoglobin (Hb) consists of an iron-containing heme ring and four globin chains: two α and two non-α.

The composition of the four globin chains determines the Hb type.

Normal Haemoglobin

  • HbA - α2β2 Adult HbA
  • HbA2 - α2δ2
  • HbF – α2γ2 Fetal Hb

Each goblin chain have separate genetic control

α –thalassaemia affect α-chain synthesis

β –thalassaemia affect β-chain synthesis

  • β-Thalassaemia is characterized by the deficient production of the β-globin chains of hemoglobin (Hb). This typically arises due to mutations in the β-globin gene. Over 200 mutations have been identified in this gene, and the type of mutation can influence the severity of the disease.
forms of thalassaemia
Forms of β-Thalassaemia
  • The three main forms of β-thalassaemia, in order of decreasing severity, are:
    • β-thalassaemia major (mutations in both alleles, homozygous)
    • β-thalassaemiaintermedia (diverse mutations)
    • β-thalassaemia minor (single mutation, heterozygous)
forms of thalassaemia order of severity
Forms of β-Thalassaemia – Order of severity

HSCT = hematopoietic stem cell transplantation

thalassaemia trait
Thalassaemia Trait
  • Individuals with thalassaemia trait do not require treatment or long-term monitoring. They usually do not have iron deficiency, so iron supplements will not improve their anemia. Iron therapy should only be administered if iron deficiency occurs.
  • Individuals with thalassaemia trait have a normal life expectancy.
  • Most individuals with thalassaemia trait are diagnosed when their complete blood count shows a mild microcytic anemia.
  • β-Thalassaemia trait is asymptomatic and is associated with microcytosis, usually no or mild anemia, no splenomegaly, and no bone disease

An absence or deficiency of α-chain synthesis due to delation of α-genes.

types of thalassaemia thalassaemia
Types of Thalassaemia: α-Thalassaemia

α-Thalassaemia is characterized by the deficient production of the α-globin chains of hemoglobin (Hb). This typically arises due to mutations in the α-globin gene.

Forms of α-Thalassaemia

α-Thalassaemia is one of the most common hemoglobin genetic abnormalities. It can be divided into four clinical conditions of increasing severity.

There are:

  • two carrier states, silent and trait, and
  • two clinically relevant forms, α-thalassaemia or HbH disease and Hb Bart's hydropsfetalis syndrome.
thalassaemia clinical consequences
Thalassaemia: Clinical Consequences
  • Anemia
  • Splenomegaly
  • Impaired growth and development
  • Endocrine disorders (e.g. hypogonadism, type 2 diabetes)
  • Venous and arterial thromboembolic events
  • Osteopenia
  • Osteoporosis
thalassaemia diagnosis
Thalassaemia: Diagnosis

Diagnostic methods for β-thalassaemia major include:

  • Genetic studies and prenatal diagnosis
  • Clinical history and physical examination
  • Complete blood count (CBC)
  • Blood films
  • Hb electrophoresis
  • Imaging studies
  • Differential diagnosis
treatment of thalassaemia
Treatment of Thalassaemia

Potentially Curative Treatment

  • The only potentially curative treatment option for patients with β-thalassaemia major is hematopoietic stem cell transplantation (HSCT). Therapy consists primarily of supportive therapy based on clinical manifestations.
r eferences
  • Pathogenesis and Lab Diagnosis

Presentation at Seminar on observation of World Thalassaemia Day 2009

Presentation: 10 May 2009, Dinajpur Medical College


Thank you!