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Y3 Haematology > Haemoglobinopathies and Iron Overload > Flashcards

Haemoglobinopathies and Iron Overload Flashcards

1
Q

What inheritance pattern are most haemoglobinopathies?

A

AR

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2
Q

What chromosome is the alpha chain gene on?

A

16

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3
Q

What chromosome is the beta chain gene on?

A

11

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4
Q

What investigations are done for suspected haemoglobinopathies

A

FBC
Blood film
HPLC
Gel electrophoresis

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5
Q

What is the basic mechanism behind thalassaemia?

A

Decreased globin chain synthesis causes ineffective erythropoiesis

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6
Q

What type of anaemia does thalassaemia cause?

A

Microcytic hypochromic haemolytic anaemia

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7
Q

What type of mutation causes alpha thalassaemia?

A

Deletion

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8
Q

What types of Hb are effected by alpha thalassaemia?

A

HbA
HbA2
HbF

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9
Q

What disease does alpha thalassaemia cause a slight selective pressure against?

A

Malaria

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10
Q

What are the 3 main forms of alpha thalassaemia?

A

Asymptomatic trait
HbH disease
Barts hydrops fetals

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11
Q

What alpha mutations cause asymptomatic alpha thalassaemia?

A
  • α/αα or
  • -/αα or
  • α/-α
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12
Q

What alpha chain mutation causes HbH disease?

A

–/-α

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13
Q

What is seen in asymptomatic alpha thalassaemia on HPLC and serum ferritin?

A

Normal ferritin

Normal HPLC

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14
Q

What is the Mx of asymptomatic alpha thalassaemia?

A

No Tx

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15
Q

What effect does HbH disease have on Hb?

A

Causes excess beta chain production - haemoglobin H - which can’t carry O2
Beta 4

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16
Q

How does HbH disease present?

A 
Moderate / severe anaemia
Splenomegaly
Gallstones
Intermittent jaundice
Decreased growth
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17
Q

What causes splenomegaly in HbH disease?

A

Extramedullary hematopoiesis

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18
Q

What causes intermittent jaundice in HbH disease?

A

Haemolysis due to oxidative damage

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19
Q

What effect does HbH diseases have on reticulocytes?

A

Increased numbers

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20
Q

What is seen on stain blood film in HbH disease?

A

Heinz bodies

Red cell inclusions

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21
Q

What effect does HbH disease have on MCH and MCV?

A

Decreased

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22
Q

What was the management of HbH disease in the past?

A

Splenectomy

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23
Q

What is the severest form of alpha thalassaemia?

A

Barts hydrops fetalis

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24
Q

What alpha chain mutation causes Barts hydrops fetalis?

A

–/–

No alpha chain synthesis, no HbF or HbA

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25
Q

What forms of haemoglobin are present at birth in hydrops fetalis?

A

γ4 + HbH β4 tetramers

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26
Q

Most cases of hydrops fetalis die in utero. T or F

A

True

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27
Q

What type of mutation causes beta thalassaemia?

A

Point mutation

28
Q

What forms of Hb are effected by beta thalassaemia?

A

Only HbA

29
Q

What are the 3 forms of beta thalassaemia?

A

β thalassaemia trait
β thalassaemia intermedia
β thalassaemia major

30
Q

What mutations cause β thalassaemia trait?

A

β+/β b-/bb

β0/β –/bb

31
Q

What mutations cause β thalassaemia intermedia?

A

β+/β+ -b/-b

β0/β+ –/-b

32
Q

What mutations cause β thalassaemia major?

A

β0/β0 –/–

33
Q

How does β thalassaemia trait present?

A

No S+S

34
Q

What effect does β thalassaemia trait have on MCV, MCH, HbA2 and ferritin?

A

Low MCV
Low MCH
Raised HbA2
Normal ferritin

35
Q

What are the pathological consequences of β thalassaemia major?

A

Extramedullary haematopoiesis
Chronic erythroid hyperplasia
Organ damage

36
Q

How old are patients when β thalassaemia major presents?

A

6 - 24 months

Should be more HbA

37
Q

How does β thalassaemia major present?

A 
Pallor
Failure to thrive
Splenomegaly
Bone deformity
Frontal bossing
SC compression
38
Q

What effect does β thalassaemia major have on Hb, MCV, WCC, platelets and ferritin?

A 
Low Hb
Low MCV
Normal WCC
Low platelets
Normal ferritin
39
Q

What is seen on blood film in β thalassaemia major?

A

Pappenheimer bodies

40
Q

What is the Mx of β thalassaemia major?

A

Lifelong regular transfusion

41
Q

What is the purpose of transfusions in β thalassaemia major?

A

Prevent iron overload and ineffective erythropoiesis

42
Q

What is the highest cause of mortality in beta thalassaemia?

A

Fe overload

43
Q

How does Fe overload present?

A 
Impaired growth
DM
OP
Cardiomyopathy
Arrhythmia
Cirrhosis
Hepatocellular carcinoma
44
Q

What is the Fe chelating drug given SC or IV that causes Fe complex excretion?

A

Desferrioxamine

45
Q

Why type of mutation causes sickling disorders?

A

Point mutation

46
Q

A mutation of glutamine to valine producing βS causes what group of disorders?

A

Sickling disorders

47
Q

What mutation causes sickle trait?

A

1 abnormal β gene β/βs

48
Q

What are the symptoms of sickle trait?

A

Asymptomatic

May sickle in severe hypoxia eg altitude

49
Q

What is seen on blood film in sickle trait?

A

Normal

50
Q

What effect does sickle trait have on MCH?

A

Normal

51
Q

What mutation causes sickle cell anaemia? What is the mode of inheritance?

A

Autosomal recessive

βs/βs

52
Q

What consequences does sickle cell anaemia have on Hb?

A

No HbA

>80% HbS

53
Q

What effect does sickle cell anaemia have on:

  • the spleen
  • RBC lifespan
  • iron
A

Hyposplenism if repeated infarcts

Decreased RBC lifespan

No Fe overload

54
Q

What is the pathology of a sickle crisis?

A

BV occlusion; infarct

55
Q

What are the common sites of sickle crisis?

Triggered by hypoxia, dehydration, infection, hypothermia, fatigue

A 
Dactylitis digits
Bone marrow
Lung
Spleen
CNS
56
Q

What drug is given as prophylaxis in sickle cell anaemia hyposplenism?

A

Penicillin since increased infection risk

57
Q

What is sickle cell disease

A

Heterozygous HbS + diff β chain mutation

58
Q

What condition causes a primary iron overload?

A

Hereditary haemochromatosis

most autosomal recessive

59
Q

What effect does hereditary haemochromatosis have on hepcidin, transferrin saturation and serum ferritin?

A

Low hepcidin
Transferrin saturation more than 50%
Serum ferritin more than 300 in M and 200 in F

60
Q

Hereditary haemochromatosis generally presents in people age _____. It is mostly asymptomatic until there is ______

A

Middle age

Irreversible organ damage

61
Q

Iron overload greater than 5 grams causes _______ which causes increased free radicals

A

Oxidative stress

62
Q

What is the Mx of hereditary haemochromatosis?

A

Weekly venesection 450-500ml

63
Q

Iron overload causes irreversible organ damage. Which organs are effected and how does this present?

A 
Cirrhosis
Cardiomyopathy
Impotence
Arthralgia
DM
64
Q

What is the iatrogenic cause of secondary iron overload?

A

Regular RBC transfusions

65
Q

Why is venesection not the management of secondary iron overload?

A

Already anaemic

66
Q

What is the management of secondary iron overload?

A

Iron chelating drugs

67
Q

What is the SC / IV iron chelating agent?

A

Desferrioxamine

Y3 Haematology (15 decks)

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