Thalassaemia

Question 1

Alpha thalassaemia

Types of disease

Answer 1

If 1 or 2 alpha globulin alleles are affected then the blood picture would be hypochromic and microcytic, but the Hb level would be typically normal

If are 3 alpha globulin alleles are affected results in a hypochromic microcytic anaemia with splenomegaly. This is known as Hb H disease

If all 4 alpha globulin alleles are affected (i.e. homozygote) then death in utero (hydrops fetalis, Bart’s hydrops)

Question 2

What is thalassaemia?

Genetics

Answer 2

The thalassaemias are a group of genetic disorders characterised by a reduced production rate of either alpha or beta chains

Both are autosomal recessive [ThalaSSaemia and receSSive]

Question 3

Types of beta thalassaemia

Answer 3

Beta thalassaemia trait

Beta thalassaemia major

Question 4

General complications of thalassamia

Answer 4

Haemolysis resulting in:

• Jaundice (high billirubin)
• Secondary haemochromatosis (high iron)
  [diabetes, cirrhosis, hypothyroidism, cardiac arrhythmias, pericarditis]
• Increased formation of RBC so enlargement of spleen, bone marrow (including in skull)

Question 5

Beta thalassamia major

Genes

Answer 5

Genetics: two of the recessive genes

so absence of beta chains (chromosome 11)

Question 6

Beta thalassamia major

CLinical features

Answer 6

• presents in first year of life with failure to thrive (because before then fetal Hb is still being produced)
• Facies: chipmunk (enlarged forehead and maxilla)
• Skull xray: hair on end
• hepatosplenomegaly

Question 7

Beta thalassamia investigations

Answer 7

Bloods

• microcytic anaemia
• high Fe, ferritin and

Blood film:

• hypochromic cells
• Target cells: due to scrunching up of the excessive membrane

Electrophoresis:

• HbA2 and HbF raised
• HbA absent

Question 8

Management

Answer 8

Repeat blood transfusion

SC desferrioxamine (iron chelating agent to stop iron overload)

Splenectomy if needed