Haemoglobinopathy

Question 1

Describe the structure of haemoglobin?

Answer 1

2 alpha globin like chains

2 beta globin like chains

Question 2

What is the ratio of haem to globin in haemaglobin?

Answer 2

One haem attached to each globin chain

Question 3

What chromosome is the alpha like gene expressed on?

Answer 3

16

Question 4

What chromosome is the beta like gene expressed on?

Answer 4

11

Question 5

At what age do you reach adult levels of haemaglobin?

Answer 5

6 - 12 months

Question 6

What are the two main groups of haemaglobinopathies?

Answer 6

Thalassaemia - decreased rate of globin chain production

Structural haemoglobin variants - normal production of structurally abnormal globin chains

Question 7

What are the two types of thalassaemias?

Answer 7

Alpha thalassaemia

Beta thalassaemia

Question 8

What kind of anaemia do you get with thalassaemia?

Answer 8

Microcytic hypochromic anaemia

Question 9

Why do you get alpha thalassaemia?

Answer 9

Deletion of one or both of the alpha genes from chromosome 16

Question 10

Why do you get reduced synthesis alpha thalassaemia?

Answer 10

Deletion of one of the alpha genes from chromosome 16

Question 11

Why do you get absent synthesis alpha thalassaemia

Answer 11

deletion of both genes from chromsome 16

Question 12

What is the most severe form of alpha thalassaemia?

Answer 12

HbH disease

only 1 working alpha gene per cell

Question 13

What supplement do you need to give in alpha thalassaemia?

Answer 13

Folic acid (increased RNC turnover creates an increased demand)

Question 14

How is beta thalassaemia usually caused?

Answer 14

Point mutation

Question 15

How is beta thalassamia inherited?

Answer 15

Autosomal recessive

Question 16

What is the diagnostic test for beta thalassaemia trait?

Answer 16

Raised HbA2

Question 17

What does bet thalassaemia lead to if not diagnosed early?

Answer 17

Extramedullary haematopoiesis

Question 18

How do you manage beta thalassaemia?

Answer 18

Regular transfusions to maintain the haemoglobin above 95g/L so as to suppress ineffective arythropoiesis and inhibit gut over absorption of iron.

Question 19

What drugs are given in beta thalassaemia?

Answer 19

Iron

Iron cheleating drugs such as desferrioxamine

Question 20

How is sickle cell anaemia inherited?

Answer 20

Autosomal recessive

Question 21

What kind of mutation is seen in sickle cell anaemia?

Answer 21

Point mutation in codon 6 of the beta globin gene

Question 22

How many abnormal genes do you have in sickle cell trait?

Answer 22

One

Question 23

What are the precipitants of a sickle crisis?

Answer 23

Hypoxia
Dehydration
Infection
Cold exposure
Stress/Fatigue

Question 24

What are the symptoms of sickle cell disease?

Answer 24

Tissue infarction due to vascular occlusion (symptoms dependent on site and severity)

• Digits
• Leg ulcers
• Sever pain

Question 25

What is the treatment of a painful sickle cell crisis?

Answer 25

Opiate analgesis
Hydration
rest
Oxygen
Antibiotics if infection
Red cell exchange transfusion in sever crisis (chest crisis or neurological crisis)

Question 26

What are the long term effects of sickle cell disease?

Answer 26

Poor growth
Infection (hyposplenism)
Organ damage
Psychosocial problems