Thalassemias

Question 1

what does thalassaemia result in?

Answer 1

microcytic anaemia

Question 2

what is the consequence of accumulation of globin chains?

Answer 2

ineffective erythropoiesis + haemolysis

Question 3

what is the cause of alpha thalassaemia?

Answer 3

deletion of alpha genes from chromosome 16

Question 4

alpha chains are present in which forms of Hb?

Answer 4

HbA, HbA2 and HbF

Question 5

what is the genes of someone unaffected by alpha thalassaemia?

Answer 5

4 normal α genes (αα/αα)

Question 6

how many genes are missing in alpha thalassemia trait?

Answer 6

one or two genes missing

Question 7

what are the genes of someone with alpha thalassaemia trait?

Answer 7

α+/α (-α/αα)
α0/ α (–/αα)
α+/α+(-α/-α)

Question 8

what are the clinical features of someone with alpha thalassemia trait?

Answer 8

Asymptomatic

Microcytic, hypochromic red cells with mild anaemia

Question 9

what is the disease associated with only one alpha gene left?

Answer 9

HbH disease

Question 10

what are the genes of someone with HbH disease?

Answer 10

α0/α+(–/-α )

Question 11

what is the characteristic feature of HbH disease?

Answer 11

formation of HbH

Question 12

what is the pathophysiology of HbH disease?

Answer 12

Excess β chains form tetramers (β4) called HbH which can’t carry oxygen

Question 13

what are the clinical features of HbH disease?

Answer 13

Severe
Anaemia - moderate anaemia to transfusion dependent
Splenomegaly
Jaundice - Haemolysis, Ineffective erythropoiesis

Question 14

what can be seen histologically in HbH disease?

Answer 14

 Red cell inclusions of HbH

Question 15

what is the anaemia associated with HbH?

Answer 15

microcytic

Question 16

what are the MCV and MCH in HbH?

Answer 16

very low

Question 17

what is the disease associated with no functional alpha genes?

Answer 17

Hb Barts hydrops fetalis

Question 18

what are the genes of someone with Hb Barts hydrops fetalis disease?

Answer 18

α0/α0 (–/–)

Question 19

what is the characteristic feature of Hb Barts?

Answer 19

Hb (y4)

Question 20

what are the haemoglobin types found in Hb Barts at birth?

Answer 20

Hb Barts (γ4) and HbH (β4)

Question 21

what are the clinical features of Hb Barts Hydrops Fetalis?

Answer 21

Severe anaemia
Cardiac failure
Growth retardation
Severe hepatosplenomegaly
Skeletal and cardiovascular abnormalities
Almost all die in utero

Question 22

what does the blood film in Hb Barts Hydrops Fetalis?

Answer 22

numerous nucleated RBCs

Question 23

what is beta thalassaemia?

Answer 23

Disorder of beta chain synthesis

Question 24

which haemoglobin is affected in beta thalassaemia?

Answer 24

HbA (α2β2)

Question 25

what are are the genes of someone with B thalassaemia trait?

Answer 25

(β+/β or β0/β)

Question 26

what are are the genes of someone with B thalassaemia intermedia?

Answer 26

(β+/β+ or β0/β+)

Question 27

what are are the genes of someone with B thalassaemia major?

Answer 27

(β0/β0)

Question 28

what are the clinical features of B thalassaemia trait?

Answer 28

Asymptomatic

No/Mild anaemia

Question 29

what are the MCV/MCH of B thalassaemia trait?

Answer 29

low MCV/MCH

Question 30

what are the clinical features of B thalassaemia intermedia?

Answer 30

Moderate severity

Question 31

what is the management of B thalassaemia intermedia?

Answer 31

requires occasional transfusion

Question 32

what are the clinical features of B thalassaemia major?

Answer 32

Severe
Presents 6-24 months 
Pallor, failure to thrive
Hepatosplenomegaly
Skeletal changes 
Organ damage
Cord compression

Question 33

what is the haemoglobin analysis of B thalassaemia major?

Answer 33

Mainly HbF

Minimal HbA

Question 34

what is the management of B thalassaemia major?

Answer 34

Regular transfusion programme to maintain Hb at 95-105g/l

Bone marrow transplant

Question 35

what are the risks of blood transfusion?

Answer 35

Iron overload
Viral infection - HIV, Hepatitis B and C
Transfusion reaction Increased risk of sepsis