Haemoglobinopathy Flashcards

1
Q

Describe the structure of haemoglobin?

A

2 alpha globin like chains

2 beta globin like chains

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2
Q

What is the ratio of haem to globin in haemaglobin?

A

One haem attached to each globin chain

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3
Q

What chromosome is the alpha like gene expressed on?

A

16

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4
Q

What chromosome is the beta like gene expressed on?

A

11

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5
Q

At what age do you reach adult levels of haemaglobin?

A

6 - 12 months

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6
Q

What are the two main groups of haemaglobinopathies?

A

Thalassaemia - decreased rate of globin chain production

Structural haemoglobin variants - normal production of structurally abnormal globin chains

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7
Q

What are the two types of thalassaemias?

A

Alpha thalassaemia

Beta thalassaemia

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8
Q

What kind of anaemia do you get with thalassaemia?

A

Microcytic hypochromic anaemia

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9
Q

Why do you get alpha thalassaemia?

A

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

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10
Q

Why do you get reduced synthesis alpha thalassaemia?

A

Deletion of one of the alpha genes from chromosome 16

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11
Q

Why do you get absent synthesis alpha thalassaemia

A

deletion of both genes from chromsome 16

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12
Q

What is the most severe form of alpha thalassaemia?

A

HbH disease

only 1 working alpha gene per cell

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13
Q

What supplement do you need to give in alpha thalassaemia?

A

Folic acid (increased RNC turnover creates an increased demand)

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14
Q

How is beta thalassaemia usually caused?

A

Point mutation

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15
Q

How is beta thalassamia inherited?

A

Autosomal recessive

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16
Q

What is the diagnostic test for beta thalassaemia trait?

A

Raised HbA2

17
Q

What does bet thalassaemia lead to if not diagnosed early?

A

Extramedullary haematopoiesis

18
Q

How do you manage beta thalassaemia?

A

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

19
Q

What drugs are given in beta thalassaemia?

A

Iron

Iron cheleating drugs such as desferrioxamine

20
Q

How is sickle cell anaemia inherited?

A

Autosomal recessive

21
Q

What kind of mutation is seen in sickle cell anaemia?

A

Point mutation in codon 6 of the beta globin gene

22
Q

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

A

One

23
Q

What are the precipitants of a sickle crisis?

A
Hypoxia
Dehydration
Infection
Cold exposure
Stress/Fatigue
24
Q

What are the symptoms of sickle cell disease?

A

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

  • Digits
  • Leg ulcers
  • Sever pain
25
Q

What is the treatment of a painful sickle cell crisis?

A
Opiate analgesis
Hydration
rest
Oxygen
Antibiotics if infection
Red cell exchange transfusion in sever crisis (chest crisis or neurological crisis)
26
Q

What are the long term effects of sickle cell disease?

A

Poor growth
Infection (hyposplenism)
Organ damage
Psychosocial problems