Page 112 - Essential Haematology

98 / Chapter 7 Genetic disorders of haemoglobin

Treatment MCH very low) but high red cell count
12

1 Regular blood transfusions are needed to main- ( > 5.5 × 10 /L) and mild anaemia (haemoglobin

tain the haemoglobin over 10 g/dL at all times. 10 – 12 g/dL). It is usually more severe than α -

This usually requires 2 – 3 units every 4 – 6 weeks. thalassaemia trait. A raised Hb A 2 ( > 3.5%) confi rms

Blood, filtered to remove white cells, gives the the diagnosis. One of the most important indica-

fewest reactions. The patients should be geno- tions for making the diagnosis is that it allows the

typed at the start of the transfusion programme possibility of prenatal counselling to patients with
in case red cell antibodies against transfused red a partner who also has a signifi cant haemoglobin
cells develop. disorder. If both carry β - thalassaemia trait there is
2 Regular folic acid (e.g. 5 mg/day) is given if the a 25% risk of having a child with thalassaemia
diet is poor. major.
3 Iron chelation therapy (see Chapter 4 ).
4 Splenectomy may be needed to reduce blood
Thalassaemia i ntermedia

requirements. This should be delayed until the
patient is over 6 years old because of the high risk Cases of thalassaemia of moderate severity (haemo-
of dangerous infections post - splenectomy. Th e globin 7.0 – 10.0 g/dL) who do not need regular
vaccinations and antibiotics to be given are transfusions are called thalassaemia intermedia

described in Chapter 10 . (Table 7.3 ). This is a clinical syndrome which may
5 Endocrine therapy is given either as replacement be caused by a variety of genetic defects: homozygous

because of end - organ failure or to stimulate the β - thalassaemia with production of more Hb F than

pituitary if puberty is delayed. Diabetic patients usual, e.g. from mutations of the BCL11A gene or
will require insulin therapy. Patients with oste- with mild defects in β - chain synthesis, by β -
oporosis may need additional therapy with thalassaemia trait alone of unusual severity ( domi-
‘
increased calcium and vitamin D in their diet, nant ’ β - thalassaemia) or β - thalassaemia trait in
together with a bisphosphonate and appropriate association with mild globin abnormalities such as

endocrine therapy. Hb Lepore. The coexistence of α - thalassaemia trait

6 Immunization against hepatitis B should be improves the haemoglobin level in homozygous

carried out in all non - immune patients. Treatment β - thalassaemia by reducing the degree of chain

for transfusion - transmitted hepatitis C with α - imbalance and thus of α - chain precipitation and
interferon, ribavirin and newer antivirals is
needed if viral genomes are detected in plasma. Table 7.3 Thalassaemia intermedia.

7 Allogeneic stem cell transplantation off ers the
prospect of permanent cure. The success rate Homozygous β - thalassaemia

+

(long - term thalassaemia major - free survival) is Homozygous mild β - thalassaemia

over 80 – 90% in well - chelated younger patients Coinheritance of α - thalassaemia
without liver fibrosis or hepatomegaly. A human Enhanced ability to make fetal haemoglobin

leucocyte antigen (HLA) matching sibling (or ( γ - chain production)
rarely other family member or matching unre- Heterozygous β - thalassaemia

lated donor) acts as donor. Failure is mainly a Coinheritance of additional α - globin genes

result of recurrence of thalassaemia, death (e.g. ( α α α / α α or α α α / α α α )

from infection) or severe chronic graft - versus - Dominant β - thalassaemia trait

host disease.

δ β - Thalassaemia and hereditary persistence of

fetal haemoglobin

β - Thalassaemia t rait ( m inor) Homozygous δ β - thalassaemia

Heterozygous δ β - thalassaemia/ β - thalassaemia

This is a common, usually symptomless, abnormal- Homozygous Hb Lepore (some cases)
ity characterized like α - thalassaemia trait by a
Haemoglobin H disease
hypochromic microcytic blood picture (MCV and