Haematology: Beta Thalassaemias

Question 1

What are the 2 main types?

Answer 1

Beta thalassaemia major

Beta thalassaemia intermedia

Question 2

What are the 2 main types characterised by?

Answer 2

A severe reduction in the production of beta globin and thereby HbA production

Question 3

Beta thalassaemias occur most often in people from…

Answer 3

The Indian subcontinent, Mediterranean and Middle East

Question 4

What is the most severe form of the disease?

Answer 4

Beta thalassaemia major

HbA cannot be produced because of the abnormal beta globin gene

Question 5

Describe beta thalassaemia intermedia

Answer 5

Milder form and variable severity

The beta globin mutations allow a small amount of HbA and/or a large amount of HbF to be produced

Question 6

What clinical features are associated?

Answer 6

Severe anaemia which is transfusion dependent
Jaundice
In absence of regular blood transfusion: hepatosplenomegaly, bone marrow expansion
Bossing of skull and maxillary overgrowth (rare)

Question 7

How is beta thalassaemia major treated?

Answer 7

Fatal without regular blood transfusion
Lifelong monthly transfusion of RBCs - aim to maintain Hb over 100g/L to reduce growth failure and prevent bone deformity

Question 8

What can repeat blood transfusions cause?

Answer 8

Chronic iron overload - if untreated can cause cardiomyopathy, liver cirrhosis, diabetes (due to iron deposition in pancreas) infertility and growth failure (due to deposition in pituitary gland), skin hyperpigmentation
Antibody formation - allo-antibodies to transfused red cells make finding compatible blood difficult
Infection - now uncommon (hepA,B,C, HIV, prions)
Venous access - central venous access may be required

Question 9

What do all those receiving repeated transfusions require?

Answer 9

All patients treated with chelating agents - subcutaneous desferrioxamine or oral iron chelator starting from 2-3 years of age

Iron lost in urine/faeces

Question 10

What is the only cure?

Answer 10

Bone marrow transplant

Question 11

For parents who are both heterozygous for beta thalassaemia, what should be offered?

Answer 11

Prenatal diagnosis via DNA analysis of chorionic villus sample and genetic counselling - there is a 1 in 4 risk of having a child with beta thalassaemia

Question 12

Describe beta thalassaemia trait

Answer 12

= heterozygous
Usually asymptomatic
Red cells are hypochromic and microcytic
Anaemia mild or absent with disproportionate reduction in MCH and MCV
Raised HbA2 and mild elevation of HbF
Serum ferritin not low