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Haematology Week 1 2018/19 > 6: Haemoglobinopathies > Flashcards

6: Haemoglobinopathies Flashcards

1
Q

Which globin chains are found in

a) adult Hb
b) foetal Hb?

A

a) 2 alpha, 2 beta

b) 2 alpha, 2 gamma

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2
Q

Which type of haemoglobin is most common in adults?

A

HbA

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3
Q

Which chromosomes code for

a) alpha chains
b) beta chains?

A

a) Alpha chains - chromosome 16

b) Beta chains - chromosome 11

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4
Q

Which genetic process causes HbF production to switch to HbA production?

A

Gene silencing

On chromosomes 16 and 11

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5
Q

What is a haemoglobinopathy?

A

Inherited conditions affecting globin chain synthesis

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6
Q

What is the common mode of inheritance of haemoglobinopathies?

A

Autosomal recessive

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7
Q

What is thalassaemia?

A

Decreased rate of globin chain synthesis

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8
Q

What types of thalassaemia affect the rate of production of

a) alpha chains
b) beta chains?

A

a) Alpha thalassaemia
b) Beta thalassaemia

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9
Q

___ ___ are toxic in high concentrations.

A

Globin chains

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10
Q

Accumulation of globin chains leads to ineffective erythropoiesis - what does this mean?

A

RBC precursors die before they can develop properly due to toxicity

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11
Q

How many alpha chain genes exist on chromosome 16?

A

4

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12
Q

How many beta chain genes exist on chromosome 11?

A

2

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13
Q

The more alpha genes which are deleted, the (faster / slower) the rate of alpha globin production.

A

slower

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14
Q

How many alpha genes are lost from chromosome 16 to cause HbH disease?

A

3

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15
Q

What is meant by HbH in HbH disease?

A

Dysfunctional type of haemoglobin made up of 4 beta chains

because alpha chains aren’t produced fast enough

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16
Q

What is the most severe form of alpha thalassaemia?

What is the cause?

A

Barts hydrops foetalis

Deletion of all 4 alpha genes from chromosome 16

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17
Q

Is Barts hydrops foetalis compatible with life?

A

No

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18
Q

What disease is caused by point mutations in the beta globulin genes of chromosome 9?

A

Beta thalassaemia

19
Q

Which types of haemoglobin are affected by

a) alpha thalassaemia
b) beta thalassaemia?

A

a) All of them (HbA, HbF etc.) because they all contain alpha chains

b) HbA only

20
Q

What are the three classifications of beta thalassaemia?

A

Beta thalassaemia trait

Beta thalassaemia intermedia

Beta thalassaemia major

Increasing in severity as you go

21
Q

When does beta thalassaemia major present?

A

Around 6 months, when HbF should be changing to HbA

22
Q

How is beta thalassaemia major treated?

A

Blood transfusions to maintain haemoglobin concentration

23
Q

What is a side effect of regular blood transfusions in beta thalassaemia major?

A

Iron overload

24
Q

How is iron overload secondary to blood transfusions treated?

A

Iron chelating drugs

chelate: to form a solution and excrete via urine

25
Q

What genetic mutation causes sickle cell anaemia?

A

Substitution in codon 6 of beta gene in chromosome 9

Glutamine to valine

26
Q

What type of haemoglobin is produced in sickle cell disease?

A

HbS

crap structure, crap shape, ‘polymerised’, damages the cell membrane

27
Q

What happens if you have a heterozygous sickle cell mutation?

A

Sickle cell trait

Most likely asymptomatic but you can pass the gene on

28
Q

What is the mode of inheritance of sickle cell anaemia?

A

Autosomal recessive

29
Q

Sickle cells have a shortened ___ ___.

What process does this cause?

A

shortened life span

haemolysis

30
Q

What is an acute problem seen in sickle cell anaemia?

A

Infarctions caused by sickle cells occluding circulation - sickle cell crisis

Can affect spleen causing hyposplenism

31
Q

What are some triggers of sickle cell crisis?

A

Hypoxia

Dehydration

Cold

Infection

32
Q

How is a sickle crisis managed?

A

Analgesia

Hydration

Oxygen

Blood transfusion if severe

33
Q

What is a complication of hyposplenism secondary to sickle cell anaemia?

A

Infection

34
Q

What are the two main causes of microcytic anaemia?

A

Iron deficiency

Thalassaemia

less common: congenital sideroblastic anaemia, lead poisoning

35
Q

What would be seen on a FBC of a patient with thalassaemia?

A

Microcytic hypochromic anaemia

36
Q

Sickle cell anaemia and thalassaemia are ___ for in pregnant women and their partners.

A

screened

37
Q

What is the mode of inheritance of most types of haemoglobinopathy?

A

Autosomal recessive

38
Q

Which types of haemoglobin are affected in

a) alpha thalassaemia
b) beta thalassaemia?

A

a) HbA, HbA2 and HbF (i.e all of them)

b) HbA only

39
Q

The loss of up to ___ alpha globin genes results in asymptomatic alpha thalassaemia.

A

up to two

40
Q

What type of anaemia does thalassaemia cause?

A

Microcytic, hypochromic anaemia

41
Q

Both iron deficiency and thalassaemia cause microcytic anaemia.

How would you differentiate them?

A

Check ferritin levels

Low - probably iron deficiency

42
Q

What are the clinical features of HbH disease?

A

Anaemia

Splenomegaly

Jaundice

43
Q

What occurs in the fingers of sickle crisis patients?

A

Dactylitis

painful inflamed digits

Haematology Week 1 2018/19 (9 decks)

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