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Y3 Haematology > Haemoglobinopathies and Iron Overload > Flashcards

Haemoglobinopathies and Iron Overload Flashcards

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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
What forms of haemoglobin are present at birth in hydrops fetalis?
γ4 + HbH β4 tetramers
26
Most cases of hydrops fetalis die in utero. T or F
True
27
What type of mutation causes beta thalassaemia?
Point mutation
28
What forms of Hb are effected by beta thalassaemia?
Only HbA
29
What are the 3 forms of beta thalassaemia?
β thalassaemia trait β thalassaemia intermedia β thalassaemia major
30
What mutations cause β thalassaemia trait?
β+/β b-/bb | β0/β --/bb
31
What mutations cause β thalassaemia intermedia?
β+/β+ -b/-b | β0/β+ --/-b
32
What mutations cause β thalassaemia major?
β0/β0 --/--
33
How does β thalassaemia trait present?
No S+S
34
What effect does β thalassaemia trait have on MCV, MCH, HbA2 and ferritin?
Low MCV Low MCH Raised HbA2 Normal ferritin
35
What are the pathological consequences of β thalassaemia major?
Extramedullary haematopoiesis Chronic erythroid hyperplasia Organ damage
36
How old are patients when β thalassaemia major presents?
6 - 24 months | Should be more HbA
37
How does β thalassaemia major present?
``` Pallor Failure to thrive Splenomegaly Bone deformity Frontal bossing SC compression ```
38
What effect does β thalassaemia major have on Hb, MCV, WCC, platelets and ferritin?
``` Low Hb Low MCV Normal WCC Low platelets Normal ferritin ```
39
What is seen on blood film in β thalassaemia major?
Pappenheimer bodies
40
What is the Mx of β thalassaemia major?
Lifelong regular transfusion
41
What is the purpose of transfusions in β thalassaemia major?
Prevent iron overload and ineffective erythropoiesis
42
What is the highest cause of mortality in beta thalassaemia?
Fe overload
43
How does Fe overload present?
``` Impaired growth DM OP Cardiomyopathy Arrhythmia Cirrhosis Hepatocellular carcinoma ```
44
What is the Fe chelating drug given SC or IV that causes Fe complex excretion?
Desferrioxamine
45
Why type of mutation causes sickling disorders?
Point mutation
46
A mutation of glutamine to valine producing βS causes what group of disorders?
Sickling disorders
47
What mutation causes sickle trait?
1 abnormal β gene β/βs
48
What are the symptoms of sickle trait?
Asymptomatic May sickle in severe hypoxia eg altitude
49
What is seen on blood film in sickle trait?
Normal
50
What effect does sickle trait have on MCH?
Normal
51
What mutation causes sickle cell anaemia? What is the mode of inheritance?
Autosomal recessive | βs/βs
52
What consequences does sickle cell anaemia have on Hb?
No HbA | >80% HbS
53
What effect does sickle cell anaemia have on: - the spleen - RBC lifespan - iron
Hyposplenism if repeated infarcts Decreased RBC lifespan No Fe overload
54
What is the pathology of a sickle crisis?
BV occlusion; infarct
55
What are the common sites of sickle crisis? Triggered by hypoxia, dehydration, infection, hypothermia, fatigue
``` Dactylitis digits Bone marrow Lung Spleen CNS ```
56
What drug is given as prophylaxis in sickle cell anaemia hyposplenism?
Penicillin since increased infection risk
57
What is sickle cell disease
Heterozygous HbS + diff β chain mutation
58
What condition causes a primary iron overload?
Hereditary haemochromatosis | most autosomal recessive
59
What effect does hereditary haemochromatosis have on hepcidin, transferrin saturation and serum ferritin?
Low hepcidin Transferrin saturation more than 50% Serum ferritin more than 300 in M and 200 in F
60
Hereditary haemochromatosis generally presents in people age _____. It is mostly asymptomatic until there is ______
Middle age | Irreversible organ damage
61
Iron overload greater than 5 grams causes _______ which causes increased free radicals
Oxidative stress
62
What is the Mx of hereditary haemochromatosis?
Weekly venesection 450-500ml
63
Iron overload causes irreversible organ damage. Which organs are effected and how does this present?
``` Cirrhosis Cardiomyopathy Impotence Arthralgia DM ```
64
What is the iatrogenic cause of secondary iron overload?
Regular RBC transfusions
65
Why is venesection not the management of secondary iron overload?
Already anaemic
66
What is the management of secondary iron overload?
Iron chelating drugs
67
What is the SC / IV iron chelating agent?
Desferrioxamine

Y3 Haematology (15 decks)

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