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Pathology (Guide) > Haematology - Haemoglobinopathies > Flashcards

Haematology - Haemoglobinopathies Flashcards

1
Q

How can you diagnose a haemoglobinopathy?

A

Through Hb electrophoresis

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2
Q

What is normal haemoglobin comprised of?

A

4 Globins arranged around a haem molecule in 2 pairs
- 4 α globin genes (2 from each parent)
- 2 β globin genes (1 from each parent)

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3
Q

What is the default Hb?

A

HbA - 95%
2 α + 2 β globins

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4
Q

What is HbA2 comprised of?

A

2 α + 2 delta globins

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5
Q

What is HbF comprised of?

A

2 α + 2 gamma globins
- Common in babies <6months

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6
Q

Which conditions affect the β globin genes?

A
  • Sickle Cell disease
  • β thalassaemia
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7
Q

Which conditions affect the α globin genes + how?

A
  • α thalassaemia
  • HbH disease
  • mutations cause deletions of α globin genes
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8
Q

What is the mode of inheritance of Sickle Cell disease?

A

Autosomal recessive

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9
Q

What is the mutation in Sickle Cell disease?

A
  • Single base mutation
  • GAG –> GTG
  • Glu –> Val at codon 6 of β chains
  • Causes HbS instead of HbA
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10
Q

What type of haemoglobin is present in sickle cell anaemia?

A

HbSS

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11
Q

What type of haemoglobin is present in sickle cell trait?

A

HbAS

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12
Q

What is sickle-haemoglobin C disease?

A
  • HbSC
  • Where one HbS is inherited from one parent and one HbC (defective β chain) is inherited from another
  • Milder than HbSS usually
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13
Q

What is sickle β thalassaemia?

A
  • HbS/β
  • HbS from one parent, β thalassaemia trait/β0 from the other
  • Similar in severity to HbSS
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14
Q

At what age does sickle cell anaemia manifest and why?

A

At 3-6 months
- Coinciddes with decreasing HbF

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15
Q

What causes sickling

A

Decreased O2 tension leads to HbS polymerisation, thus causing sickling

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16
Q

What type of haemolysis is present in a sequestration crisis?

A

Extravascular

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17
Q

What features are present in haemolysis in a sickle cell patient?

A
  • Anaemia 60-80g/L
  • Splenomegaly
  • Folate deficiency
  • Gallstones
  • Aplastic crisis (parvovirus B19)
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18
Q

What features are seen in vaso-occlusion/infarction in a sickle cell patient?

A
  • Stroke
  • Infections (hyposplenism, CKD)
  • Crises (splenic, sequestration, chest + pain)
  • Kidney (papillary necrosis, nephrotic)
  • Liver (gallstones)
  • Eyes (retinopathy)
  • Dactilitis (impaired growth)
  • Mesenteric ischaemia
  • Priapism
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19
Q

What does salmonella cause in a sickle cell patient?

A

Osteomyelitis

20
Q

What does strep. pneumoniae cause in a sickle cell patient?

A

Sepsis

21
Q

What symptoms are seen in a sickle cell child?

A
  • Strokes
  • Splenomegaly + splenic crises
  • Dactylitis
22
Q

What symptoms are seen in a sick cell teenager?

A
  • Impaired growth
  • Gallstones
  • Psych
  • Priapism
23
Q

What symptoms are seen in a sickle cell adult?

A
  • Hyposplenism
  • CKD
  • Retinopathy
  • Pulmonary hypertension
  • Iron overload (from transfusions)
24
Q

What is seen on a blood film of a sickle cell patient?

A
  • Sickle cells
  • Target cells
25
Q

Whta does a sickle solubility test show?

A

It’s positive in HbSS + HbAS

26
Q

What test is done at birth to identify sickle cell anaemia and what treatment is given?

A
  • Guthrie test
  • Pneumococcal prophylaxis
27
Q

What is the treatment for acute sickle cell anaemia?

A
  • Opioid analgesia (for painful crises)
  • Blood transfusion (usually exchange transfusion in severe crises)
28
Q

What is the treatment for chronic sickle cell anaemia?

A
  • Penicillin V
  • Pneumovax
  • HIB vaccine
  • Folic acid
  • ?Hydroxycarbamide
  • regular exchange transfusions
  • carotid doppler monitoring in early childhood
  • ?Hydroxyurea
  • ?Crizanlizumab
  • ?Voxelotor
29
Q

How does thalassaemia affect the body?

A

Unbalanced Hb synthesis leads to unmatched globins precipitate which causes haemolysis and ineffective erythropoeisis

30
Q

What is seen on a peripheral blood smear of a thalassaemic patient?

A
  • Basophilic stippling
  • Target cells
31
Q

What is the pathophysiology of β thalassaemia?

A

Point mutations in Chr 11 leads to reduced β chain synthesis which causes excess α chains

32
Q

What signs are seen in β thalassaemia?

A
  • SKULL BOSSING
  • MAXILLARY HYPERTROPHY
  • HAIRS ON END SKULL X-RAY
  • Hepatosplenomegaly
33
Q

What are the different genotypes in β thalassaemia?

A
  • B0 = no expression of gene
  • B+ = some expression of the gene
  • B = normal gene
34
Q

What are the different genotypes for β thalassaemia minor?

A
  • B/B0
  • B/B+
  • Heterozygous
35
Q

What is seen in a patient with β thalassaemia minor?

A
  • Asymptomatic (carrier)
  • Mild anaemia
36
Q

What are the different genotypes for β thalassaemia intermedia?

A
  • B+/B+
  • B+/B0
  • moderate reduction in β globin chain production
37
Q

What is seen in a patient with β thalassaemia intermedia?

A
  • Moderate anaemia
  • Splenomegaly
  • Bony deformity
  • Gallstones
38
Q

What is the genotype for β thalassaemia major?

A
  • B0/B0
  • Homozygous
39
Q

What is seen in a patient with β thalassaemia major?

A
  • 3-6mnths severe anaemia
  • FTT
  • Hepatosplenomegaly (extramedullary erythropoeisis)
  • Bony deformity
  • Severe anaemia
  • Heart failure
40
Q

How is β thalassmia diagnosed?

A
  • Guthrie test at birth
  • Hb electrophoresis
  • High performance liquid chromatography
41
Q

What is the treatment for β thalassaemia?

A
  • Minor + some intermedia don’t need regular Tx
  • Blood transfusion with iron chelation (to prevent overload)
  • Folic acid
  • Regular screening for iron overload in heart + liver
42
Q

What is the pathophysiology of α thalassaemia?

A

Deletions in Chr16 cause reduced α chain synthesis, resulting in excess β chains

43
Q

What are the different types of α thalassaemia and how are they differentiated?

A
  • α thalassaemia trait: 1/2 deletions
  • HbH disease: 3 deletions
  • Hydrops foetalis: 4 deletions
44
Q

What is seen in a patient with α thalassaemia trait?

A
  • Asymptomatic
  • Mild anaemia

If 1 deletion = silent
If 2 deletions = trait

45
Q

What is seen in a patient with HbH disease?

A
  • Moderate anaemia
  • Splenomegaly
46
Q

What is seen in a patient with hydrops foetalis?

A
  • Incompatible with life

(also known as HbBarts)

47
Q

What is the management of a patient with α thalassaemia?

A
  • Trait doesn’t need regular Tx
  • Blood transfusion with iron chelation (to prevent overload)
  • Folic acid
  • Regular screening for iron overload in heart + liver

Pathology (Guide) (84 decks)

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