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YR3: Haematology > Thalassemia > Flashcards

Thalassemia Flashcards

1
Q

What is Thalassemia?

A

Group of genetic disorders characterised by reduced globin chain synthesis
Under or no production of 1 globin chain
Unmatched globins precipitate, damaging RBC membranes causing their haemolysis whilst still in the marrow

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2
Q

Describe the inheritance of Thalassemia

A

Autosomal recessive

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3
Q

Where is the B globin gene located?

A

Chr11

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4
Q

Where is the A globin gene located?

A

Chr16

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5
Q

Describe the aetiology of Thalassemia

A

Imbalance of globin chain production + deposition in erythroblasts+ erythrocytes (membrane damage + cell destruction due to imbalance between globin chains)

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6
Q

What does imbalance in chain production in Thalassemia lead to?

A

Ineffective erythropoiesis
Haemolysis
Anaemia
Extramedullary haematopoiesis

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7
Q

What is Alpha Thalassemia?

A

Reduction in alpha-globin chain synthesis.

4 alpha-globin genes on the chromosome.

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8
Q

What are the different types of Alpha Thalassemia according to number of gene deletions?

A 
4= Hb Barts Hydrops Fetalis (intrauterine death) 
3= Hb H: microcytic hypochromic anaemia + splenomegaly 
2= Alpha 0 thalassemia: microcytic hypochromic red cells, NO ANAEMIA 
1 = Alpha+ thalassemia: microcytic hypochromic red cells, NO ANAEMIA
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9
Q

What is Beta Thalassemia major?

A

Homozygous beta thalassemia

Little or no beta-chain synthesis

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10
Q

What is Beta Thalassemia intermedia?

A

Mild defect in B-chain synthesis due to e.g. co-inheritance of B thalassemia trait with another haemoglobinopathy like HbC, leads to:
Microcytic anaemia
Reduced alpha-chain synthesis
Increased gamma-chain synthesis

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11
Q

What is Beta Thalassemia trait?

A

Heterozygous carrier state
ASYMPTOMATIC
Mild microcytic anaemia
Increased red cell count

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12
Q

Describe the epidemiology of Thalassemia

A

WORLDWIDE

Most common in the MEDITERRANEAN + areas of the Middle-East

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13
Q

List 5 signs of Beta Thalassemia major

A 
Pallor 
Malaise  
Severe anaemia  
Failure to thrive  
Prone to infection
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14
Q

When do symptoms of Beta Thalassemia present? Why?

A

3-6 months

Change from HbF (2alpha2gamma) to HbA (2alpha2beta)

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15
Q

Describe symptoms of Alpha Thalassemia

A

Symptoms of anaemia

Hb H disease: Growth retardation + Sx of gallstones: abdo pain, bloating + wind

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16
Q

How may Alpha or Beta Thalassemia trait present?

A

May be ASYMPTOMATIC

Detected during routine blood tests or due to FH

17
Q

List 5 clinical signs of Beta Thalassemia Major

A 
Dyspnoea 
Mild jaundice  
Thalassaemia facies 
Hepatosplenomegaly 
Osteopenia
18
Q

List 4 signs of HbH Alpha Thalassemia

A

Jaundice at birth
Chronic hemolytic anemia
Hepatosplenomegaly
Skeletal deformities (less common)

19
Q

What is seen on FBC in Thalassemia?

A 
Low Hb  
Low MCV (microcytic anaemia) 
Low MCH 
Normal RDW
WBC count + plts elevated due to BM hyperplasia
20
Q

What is seen on blood film in Alpha Thalassemia?

A 
Hypochromic microcytic anaemia 
Target cells + basophilic strippling 
Howell jolly bodies 
Nucleated red cells  
High reticulocyte count 
Teardrop cells
Anisopoikilocytosis
21
Q

What is seen on blood film in Beta Thalassemia?

A 
Hypochromic microcytic anaemia 
Howell jolly bodies 
Nucleated red cells  
High reticulocyte count
Teardrop cells
Anisopoikilocytosis
22
Q

What is seen on Hb electrophoreses in Beta Thalassemia?

A

Absent or reduced HbA

High HbF + HbA2

23
Q

What is seen on Hb electrophoresis in Alpha Thalassemia?

A

Will not pick up trait

Extra peak on HPLC due to Hb H

24
Q

Describe Bone Marrow in Beta Thalassemia

A

Hypercellular

Erythroid hyperplasia

25
Q

What other investigations may be used in Thalassemia?

A 
Genetic Testing (rarely) 
LFTs: raised in B-thalassemia major/ intermedia (high unconjugated BR, high LDH) 
Skull X-Ray
26
Q

What is seen on skull x-ray in Beta Thalassemia major?

A

‘Hair on end’ appearance

Caused by expansion of marrow into the cortex

27
Q

What causes hepatosplenomegaly in B thalassemia major?

A

Erythrocyte pooling + extramedullary haematopoiesis

28
Q

What causes Thalassemia facies? What are these?

A

Caused by marrow hyperplasia
High forehead
Prominent zygomatic bones, + maxilla “chipmunk”

29
Q

How do Hb electrophoresis and HPLC differ?

A

Hb-electrophoresis: qualitative analysis

HPLC: qualitative + quantitative analysis

YR3: Haematology (19 decks)

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