Thalassemia

Question 1

On what chromosome are the two alpha-globin genes usually located?

Answer 1

chromosome 16

=> 4 alpha globin genes total as 2 on each copy of chromosome 16

Question 2

If 1 or 2 alpha globin alleles is affected, what would the blood picture look like?

Answer 2

Normal Hb
Blood film = hypochromic and microcytic

Question 3

If 3 alpha-globin alleles are affected what does this cause?

Answer 3

• HbH disease
• hypochromic microcytic anaemia
• splenomegaly

Question 4

If all 4 alpha-globin alleles are affected (i.e. homozygote), what occurs?

Answer 4

death in utero
(hydrops fetalis, Bart’s hydrops)

Question 5

Beta thalassemia major is caused by the absence of beta globin alleles on what chromosome?

Answer 5

chromosome 11

Question 6

Features of beta thalassemia major

Answer 6

• failure to thrive
• hepatosplenomegaly
• microcytic anaemia
• HbA2 & HbF raised
• HbA absent

Question 7

When does beta thalassemia major usually present?

Answer 7

First year of life

Question 8

Management of beta thalassemia major

Answer 8

• repeated transfusion
  => leads to iron overload → organ failure

iron chelation therapy is important (e.g. desferrioxamine)

Question 9

How is beta thalassemia trait inherited?

Answer 9

Autosomal recessive

Question 10

Patients with beta thalassemia trait are usually asymptomatic. TRUE/FALSE?

Answer 10

TRUE
usually have a mild hypochromic, microcytic anaemia