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Gen Med (Haem) > Haemoglobinopathies > Flashcards

Haemoglobinopathies Flashcards

1
Q

The major form of haemoglobin in adults is HbA. This is composed of which haemoglobin chains?

A

2 x alpha and 2 x beta

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2
Q

The minor form of haemoglobin in adults is HbA2. This is composed of which haemoglobin chains?

A

2 x alpha and 2 x delta

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3
Q

The major form of haemoglobin the the foetus is HbF. This is composed of which haemoglobin chains?

A

2 x alpha and 2 x gamma

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4
Q

Alpha genes are located on which chromosome? How many of these genes are present per chromosome?

A

Chromosome 16- 2 genes are located on each chromosome (i.e. 4 per cell)

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5
Q

Beta genes are located on which chromosome? How many of these genes are present per chromosome?

A

Chromosome 11- 1 gene is located on each chromosome (i.e. 2 per cell)

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6
Q

Adult levels of haemoglobin should be reached by what age?

A

6-12 months

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7
Q

How are haemoglobinopathies usually inherited?

A

Autosomal recessive

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8
Q

In which type of haemoglobinopathy is there a decreased rate of structurally normal haemoglobin synthesised?

A

Thalassaemia

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9
Q

In which type of haemoglobinopathy is there a normal rate of structurally abnormal haemoglobin synthesised?

A

Structural haemoglobin variants

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10
Q

What type of anaemia is seen in individuals with thalassaemia?

A

Microcytic hypochromic anaemia

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11
Q

In thalassaemias, unbalanced accumulation of one type of globin chain leads to ineffective erythropoiesis which is toxic- this leads to what complication?

A

Haemolysis

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12
Q

What is the phenotype if an individual has 2 or 3 alpha genes present instead of the usual 4?

A

Alpha thalassaemia trait

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13
Q

What is the phenotype if an individual has 1 alpha gene present instead of the usual 4?

A

HbH disease

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14
Q

What is the phenotype if an individual has no alpha genes present instead of the usual 4?

A

Hb Bart’s hydrops foetalis

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15
Q

Do individuals with alpha thalassaemia trait usually have any symptoms? Do they require any treatment?

A

They are usually asymptomatic and don’t require any specific treatment

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16
Q

Individuals with alpha thalassamia trait may have a mild microcytic hypochromic anaemia. It is important to distinguish this from iron deficiency anaemia- how would this be done?

A

Ferritin will be normal in anaemia due to alpha thalassaemia trait

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17
Q

What is HbH?

A

Haemoglobin formed from 4 beta chains, that cannot carry oxygen

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18
Q

Red cell inclusions of HbH can be seen with special stains. How are these often described?

A

Golf ball appearance

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19
Q

What are some potential clinical features of HbH disease?

A

Moderate-severe anaemia, splenomegaly, jaundice

20
Q

How are severe cases of HbH disease treated?

A

Splenectomy +/- transfusions

21
Q

What is the typical outcome of Hb Bart’s hydrops foetalis?

A

Almost always incompatible with life

22
Q

What is the phenotype of an individual who has one reduced or one absent beta chain?

A

Beta thalassaemia trait

23
Q

What is the phenotype of an individual who has one reduced and one absent or two reduced beta chains?

A

Beta thalassaemia intermedia

24
Q

What is the phenotype of an individual who has two absent beta chains?

A

Beta thalassaemia major

25
Q

Individuals with beta thalassaemia may have an increased production of which type of haemoglobin?

A

HbA2

26
Q

What is the clinical picture of an individual with beta thalassaemia trait?

A

Asymptomatic, with no/mild anaemia

27
Q

What is the clinical picture of an individual with beta thalassaemia intermedia?

A

Moderate anaemia requiring occasional transfusions

28
Q

What is the clinical picture of an individual with beta thalassaemia major?

A

Severe anaemia with lifelong transfusion dependency

29
Q

When and how does beta thalassaemia major typically present?

A

6-24 months with pallor and failure to thrive

30
Q

Skeletal changes, causing a ‘hair on end’ appearance of the skull, is seen in which haemoglobinopathies?

A

Beta thalassaemia major and sickle cell anaemia

31
Q

What is a potential treatment for beta thalassaemia major if carried out before complications develop?

A

Bone marrow transplant

32
Q

What is the main consequence of treating severe thalassaemias with blood transfusions?

A

Iron overload

33
Q

What is given to prevent iron overload in individuals being treated with frequent blood transfusions?

A

Iron chelating agents (e.g. desferrioxamine)

34
Q

Sickle cell disorders are caused by a mutation in which gene?

A

Beta globin gene

35
Q

What is the phenotype of an individual with one normal and one abnormal beta globin gene?

A

Sickle cell trait (HbAS)

36
Q

What is the main clinical feature of sickle cell trait (HbAS)?

A

Sickling of red blood cells when exposed to hypoxia

37
Q

What is the phenotype of an individual with two abnormal beta globin genes?

A

Sickle cell anaemia (HbSS)

38
Q

What is the most common presentation of a sickle cell crisis in children?

A

Dactylitis

39
Q

How should a sickle cell crisis be treated?

A

Oxygen, fluids, opiate analgesia +/- antibiotics

40
Q

What treatment option can be used in cases of severe sickle cell crisis to decrease the concentration of HbS and improve tissue perfusion?

A

Red cell transfusion

41
Q

What effect does long-term sickle cell anaemia have on the spleen?

A

Causes hyposplenism

42
Q

How should hyposplenism as a result of sickle cell anaemia be treated?

A

Prophylactic penicillin and vaccinations against pneumococcus, haemophilus and meningococcus

43
Q

What supplements are required for individuals with sickle cell anaemia?

A

Folic acid

44
Q

How does hydroxycarbamide reduce the severity of sickle cell anaemia?

A

Induces HbF production

45
Q

What is meant by the term sickle cell disease?

A

Heterozygosity for HbS and another beta chain mutation

46
Q

What is usually the diagnostic test for haemoglobinopathies?

A

High performance liquid chromatography

47
Q

What investigation is required to test for alpha thalassaemia trait?

A

DNA testing

Gen Med (Haem) (12 decks)

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