2: A-Thalasemia Flashcards
What is A Thalasemia
deletion in one of the four alleles encoding a-globin chain - cause reduced or no a-globin
In which ethnicity is a-thalassemia more common
Asian and African
how many alleles encode a globin
4
if individuals have -a/aa how will they present
Silent carrier
if individual has two deleted alleles, what is the disease called
A-Thalasemia Trait
what is a-/-a more common in
trans-mutation = African
what is aa/– more common in
cis-mutation = Asian
what is three deleted alpha alleles called
HbH Disease
what is deletion of four deleted alpha alleles called
Barts Hydrops Foetalis
how will silent carrier present
Asymptomatic
how will alpha thalasemia trait present
Mild haemolytic anaemia
how does HbH disease present
- Jaundice and anaemia at birth
- Chronic anaemia
- Hepatosplenomegaly
what is the problem with chronic haemolytic anaemia in HbH
Requires multiple transfusions - can lead to iron overload and acquired haemochromatosis
what does deletion four alleles cause
barts hydrops foetalis
what is hydrops foetalis
collection of fluid in two or more compartments
how does Bart’s hydrops foetalis present
death in utero
describe structure adult Hb
contains two alpha and two beta chains
where are a-genes located
chromosome 16
what will be seen on FBC in a-thalasemia
microcytic anaemia
how can thalasemia and IDA be differentiated by
thalasemia - normal RDW.
IDA - increase RDW
what are two indicators of haemolysis
- Low haptoglobin
- High LDH
what will be seen on blood smear in thalasemia
Target cells
Tear drop cells
what test is used to detect thalasemia
Hb electrophoresis
what will be seen on x-ray in thalasemia
‘Hair on end appearance’ of the skull
= due to increase bone marrow proliferation to produce RBC
how is alpha thalasemia trait managed
no treatment required
how is HbH disease managed
Allogenic stem cell transplant
