Huy t h c
97
Types of
thalassaemia
Populations
affected
Causes
Investigations
Treatment
Complications
a-thalassaemia More prominent in
African and Asian
populations
¯ a-globin synthesis due to
a-globin gene mutation on
chromosome 16; this
subsequently results in excess
b-globin production
In a-thalassaemia any number
between 1 and 4 genes may
be deleted:
•
1 gene deleted = no
significant anaemia
•
2 genes deleted = trait
disease
•
3 genes deleted = HbH
disease
Blood films: in a-thalassaemia
target cells (or Mexican hat
cells) may be seen
FBC:
•
Microcytic, hypochromic
anaemia
•
¯ MCV
•
¯ MCH
•
Ferritin normal
•
Iron normal
Hb electrophoresis: - HbA
2
and - HbF
High performance
liquid chromatography
Radiology: X-ray for
bone abnormalities,
e.g. frontal bossing
Conservative: patient
education, genetic
counselling
Medical:
•
Management of
a-thalassaemia
and b-thalassaemia
is based on patient
symptoms and
overall state of
health
•
Transfusions are
usually required
when Hb <7 g/dL or
when the patient is
highly symptomatic
Iron overload
Splenomegaly
Increased risk of
infection
Heart failure
Arrhythmias
Bone abnormalities,
e.g. cranial bossing
Gallstones
TABLE 6.2 Thalassaemia
b-thalassaemia Thư ng g p
nhi u châu Âu
Đ t bi n đi m trên chu i
b-globin NST s 11;
k t qu d n t i tăng t ng h p
chu i a-globin.
b-thalassaemia có th chia
nh thành 3 đ c đi m khác
nhau:
1 Nh : thư ng không tri u
ch ng; thi u máu nh .
2 V a: Thi u máu m c đ
trung bình, không c n truy n
máu.
3 L n: thi u máu Cooley; b t
thư ng c 2 chu i b-globin
gây thi u máu n ng; đ c
trưng b i s bi n d ng xương
s do có s t o máu ngoài
t y xương.
•
Nh ng b nh nhân
truy n máu nhi u
l n có nguy cơ r i
lo n quá t i s t, do
đó c n đi u tr b ng
li u pháp kh s t;
như:
desferroxamine.
Ph u thu t:
•
C t lách
•
C y ghép t bào
g c.
•
Thi u 4 gene: t vong-
phù thai do Hb Bart.
What is thalassaemia?
Thalassaemias are genetic conditions, inherited in an autosomal recessive pattern,
that produce a picture of microcytic anaemia due to a problem in globin
chain production. This subsequently alters haemoglobin (Hb) synthesis.
Thalassaemia may be classified into a-thalassaemia and b-thalassaemia.
MAP 6.2 Thalassaemia
e.g.
g
g
g
frontal bossing
g
g
g
g
g
g
g
y
y
y
y
y p
y p
y p
y p
Table 6.2 Thalassaemia
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