The lecture has been given on Apr. 3rd, 2011 by Dr. Sabir.

1. Thalassemia
Dr. Sabir

2. Definition of Thalassemia
x The thalassemias are a diverse group of
genetic blood diseases characterized by
absent or decreased production of normal
hemoglobin, resulting in microcytic anemia
of varying degree.

3. Two Major Forms of Thalassemia
x Alpha
E Caused by a decrease in production of the
alpha-globin genes due to a deletion or
mutation of one or more of four alpha-globin
genes on chromosome 16.
x Beta
E Caused by mutations of the beta-globin genes
on chromosome 11.

4. Four Types of Alpha Thalassemia
x Silent Carrier - 3 functional genes.
x Alpha Thalassemia Trait - 2 functional &
2 non-functional genes.
x Hemoglobin H disease - 1 functional gene.
x Alpha Thalassemia Major - no functional
genes.

5. Three Types of Beta Thalassemia
x Beta Thalassemia Trait - one affected
allele of chromosome 11.
x Beta Thalassemia Intermedia - one or two
affected alleles, but only mild symptoms
experienced.
x Beta Thalassemia Major - both alleles are
affected and require blood transfusions and
drug treatments to survive.

6. History of Thalassemia
x Beta Thalassemia was first described by
Thomas Cooley, known as Cooley’s anemia
in 1925.
E Symptoms exhibited:
x Anemia
x Splenomegaly ( due to increased activity/filtering of
the red blood cells)
x Enlargement of the Liver
x Discoloration of the Skin
x Enlargement of the Cranial and Facial Bones

7. Marrow expansion
Hair on end
appearance

8. DIAGNOSTIC FEATURES OF
BETA-THALASSAEMIA
x Major
x Profound hypochromic anaemia
x Evidence of severe red cell dysplasia
x Erythroblastosis
x Absence or gross reduction of the amount of
haemoglobin A
x Raised levels of haemoglobin F
x Evidence that both parents have thalassaemia
minor

9. x Minor
x Mild anaemia
x Microcytic hypochromic erythrocytes (not iron-
deficient)
x Some target cells
x Punctate basophilia
x Raised resistance of erythrocytes to osmotic lysis
x Raised haemoglobin A2 fraction
x Evidence that one parent has thalassaemia minor

10. Differences Between Thalassemia and
Iron-deficient Anemia
x Thalassemia is x Iron-deficient anemia is
hereditary. not hereditary.
x Iron is present in the x Iron is absent in the
bone marrow. bone marrow.
x Microcytosis is usually x Microcytosis is mild or
very severe. absent.
x Basophilic stippling of x Less frequent basophilic
red blood cells is stippling of red blood
common. cells.
x Does not respond to x Responds to iron
Iron therapy. therapy.

11. Similarities Between Thalassemia and
Iron-Deficient Anemia
x Red Blood Cell fragility is decreased.
x Plasma iron may be decreased.
x Target cells are present.

12. Thalassemia and Malaria
“Malaria Hypothesis,” “the corpuscles of the
anemic heterozygote are smaller than normal, and
more resistant to hypotonic solutions. It is at least
conceivable that they are also more resistant to
attacks by the sporozoa which cause malaria.”
x Studies have shown that individuals born with the
thalassemia trait can survive malaria and pass the
trait onto the next generation.

13. TREATMENT OF BETA-
THALASSAEMIA MAJOR
1) Erythropoietic failure: Allogeneic bone
marrow transplantation from human leucocyte
antigen (HLA)-compatible sibling
Transfusion to maintain Hb > 100 g/l
Folic acid 5 mg daily
2)Iron overload: Iron therapy forbidden
Desferrioxamine therapy
3)Splenomegaly: causing mechanical problems,
excessive transfusion needs →Splenectomy

14. Prevention
x It is possible to identify a fetus with
homozygous beta-thalassaemia by obtaining
chorionic villous material for DNA analysis
sufficiently early in pregnancy to allow
termination. This examination is only
appropriate if both parents are known to be
carriers (beta-thalassaemia minor) and will
accept a termination.