Haemogloinopathies Flashcards

1
Q

What is the structure of HbA?

A

2 alpha 2 beta

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2
Q

What is the structure of HbA(2)

A

2 alpha 2 delta

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3
Q

What is the structure of HbF?

A

2 alpha 2 gamma

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4
Q

Where is the alpha globin-like gene located?

A

Chromosome 16

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5
Q

Where is the beta globin like gene located?

A

Chromosome 11

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6
Q

How are haemoglobinopathies generally inherited?

A

AR

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7
Q

What is a thalassaemia?

A

Reduced globin chain synthesis leading to inadequate Hb production

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8
Q

Which type of anaemia is seen in the thalassaemias?

A

Microcytic hypochromic

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9
Q

What is the mildest form of alpha thalassaemia called?

A

Alpha thal trait

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10
Q

What is HbH disease?

A

Only 1 functioning copy of the alpha gene

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11
Q

What is Hb Bart Hydrops fetalis?

A

No functional copies of the alpha gene

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12
Q

How does alpha thal trait present?

A

Asymptomatic

May have mild anaemia

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13
Q

What is the most severe form of alpha thalassaemia?

A

Hb Barts Hydrops fetalis

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14
Q

How does HbH disease present?

A
Splenomegaly
Jaundice
Severe anaemia 
Gall stones
Growth retardation
Iron overload
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15
Q

What happens to excess beta chains in HbH disease?

A

Form tetramers

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16
Q

How is HbH disease treated?

A

Transfusions

Maybe splenectomy

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17
Q

Where is HbH disease most common?

A

SE Asia

Middle east

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18
Q

Which kinds of Hb are found in Hb Barts Hydrops Foetalis?

A

Hb Barts

HbH

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19
Q

What is Hb Barts?

A

4 gamma chains

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20
Q

What is HbH

A

4 beta chains

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21
Q

How does Hb Barts Hydrops Foetalis present?

A

Severe anaemia
Cardiac failure
Growth retardation
Hepatosplenomegaly

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22
Q

What type of Hb is affected in beta thalassaemia?

A

HbA

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23
Q

What is the mildest form of beta thalassaemia?

A

Beta thal trait

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24
Q

How does beta thal trait normally present?

A

Asymptomatic

Mild anaemia

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25
Q

What does Hb electrophoresis show in beta thal trait?

A

Increased HbA2 and HbF

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26
Q

How does beta thal intermedia present?

A

Symptomatic anaemia

May be splenomegaly and iron overload

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27
Q

How is beta thal intermedia treated?

A

Blood transfusions

28
Q

When does beta thal major present?

A

6-24 months

29
Q

How does beta thal major present?

A

Failure to thrive

Recurrent infection

30
Q

What does extramedullary haematopoiesis cause in beta thal major?

A

Splenomegaly
Skeletal change
Organ damage

31
Q

What does Hb electrophoresis show in beta thal major?

A

Mostly HbF

32
Q

What should the target Hb be in beta thal major?

A

95-105 g/l

33
Q

How is beta thal major managed?

A

Transfusions regularly

Bone marrow transplant in kids

34
Q

What is the main cause of death in beta thal major?

A

Iron overload

35
Q

What cardiac complications may iron overload cause?

A

Arrhythmia

Cardiomyopathy

36
Q

What hepatic complications may iron overload cause?

A

Cirrhosis

Hepatocellular cancer

37
Q

What endocrine complications may iron overload cause?

A

Diabetes

Osteoporosis

38
Q

How is iron overload treated?

A

Iron chelating agents

39
Q

Give examples of iron chelating agents?

A

Desferrioxamine
Deferiprone
Deferasirox

40
Q

How is desferrioxamine given?

A

IV

s/c

41
Q

What do you need to be wary of in giving high dose desferrioxamine?

A

Ocular and ototoxicity

42
Q

How is deferiprone given?

A

Oral

43
Q

What is the main risk with deferiprone?

A

Agranulocytosis

44
Q

What are the main side effects of deferiprone?

A

Arthralgia

GI upset

45
Q

Where is the mutation in sickling disorders?

A

codon 6 of beta-globin gene

46
Q

What is the mutation in sickling disorders?

A

Glutamine to valine

47
Q

What is HbS?

A

2 alpha 2 beta (S)

48
Q

Describe the pathogenesis of sickling disorders

A

HbS polymerises when exposed to low O2 and distorts the red cell membrane

49
Q

What causes sickle crisis?

A

Distorted shape leads to impaired blood flow and prothrombotic cell adhesion to the outside
The cells get stuck in smaller arteries and cause ischaemia

50
Q

What Hb is found in sickle trait?

A

HbAS

51
Q

How does sickle trait present?

A

Asymptomatic

May have clinical features in severe hypoxia

52
Q

What does blood film show in sickle trait?

A

No abnormality

53
Q

What does electrophoresis show in sickle trait?

A

HbA

54
Q

What Hb type is seen in sickle cell anaemia?

A

HbSS

55
Q

How does sickle crisis present?

A

Severe pain
Erythema
Inflammation
All local to site of crisis

56
Q

Describe spleen activity in sickle cell anaemia?

A

Hyposplenic due to repeated infarcts

57
Q

How is acute sickle crisis treated?

A

IV fluids and morphine

58
Q

How is sickle cell anaemia treated?

A

Hydroxycarbamide

Splenectomy

59
Q

In cases of previous stroke what is considered in sickle cell anaemia?

A

Blood transfusion

60
Q

What does hydroxycarbamide do?

A

Induces HbF production

61
Q

What is given in cases of splenectomy?

A

Prophylactic life long penicillin
Folic acid
Vaccination - pneumococcus, meningococcus and haemophilus

62
Q

How may sickle cell anaemia be treated in kids?

A

Bone marrow transplant before any real damage done?

63
Q

How does sickle cell anaemia affect growth and development?

A

Short as children but regain height by adulthood

Delayed sexual maturation requiring hormone therapy

64
Q

How may sickle cell anaemia affect bone growth?

A

Chronic infarcts cause AVN of hips and shoulders

May be shortened bones in hands and feet

65
Q

What three organisms typically cause osteomyelitis in sickle cell anaemia?

A

S aureus
Strep pneumo
Salmonella