6: Haemoglobinopathies Flashcards Preview

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

Flashcards in 6: Haemoglobinopathies Deck (43)
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1

Which globin chains are found in

a) adult Hb

b) foetal Hb?

a) 2 alpha, 2 beta

b) 2 alpha, 2 gamma

2

Which type of haemoglobin is most common in adults?

HbA

3

Which chromosomes code for

a) alpha chains

b) beta chains?

a) Alpha chains - chromosome 16

b) Beta chains - chromosome 11

4

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

Gene silencing

On chromosomes 16 and 11

5

What is a haemoglobinopathy?

Inherited conditions affecting globin chain synthesis

6

What is the common mode of inheritance of haemoglobinopathies?

Autosomal recessive

7

What is thalassaemia?

Decreased rate of globin chain synthesis

8

What types of thalassaemia affect the rate of production of

a) alpha chains

b) beta chains?

a) Alpha thalassaemia

b) Beta thalassaemia

9

___ ___ are toxic in high concentrations.

Globin chains

10

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

RBC precursors die before they can develop properly due to toxicity

11

How many alpha chain genes exist on chromosome 16?

4

12

How many beta chain genes exist on chromosome 11?

2

13

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

slower

14

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

3

15

What is meant by HbH in HbH disease?

Dysfunctional type of haemoglobin made up of 4 beta chains

because alpha chains aren't produced fast enough

16

What is the most severe form of alpha thalassaemia?

What is the cause?

Barts hydrops foetalis

Deletion of all 4 alpha genes from chromosome 16

17

Is Barts hydrops foetalis compatible with life?

No

18

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

Beta thalassaemia

19

Which types of haemoglobin are affected by

a) alpha thalassaemia

b) beta thalassaemia?

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

b) HbA only

20

What are the three classifications of beta thalassaemia?

Beta thalassaemia trait

Beta thalassaemia intermedia

Beta thalassaemia major

Increasing in severity as you go

21

When does beta thalassaemia major present?

Around 6 months, when HbF should be changing to HbA

22

How is beta thalassaemia major treated?

Blood transfusions to maintain haemoglobin concentration

23

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

Iron overload

24

How is iron overload secondary to blood transfusions treated?

Iron chelating drugs

chelate: to form a solution and excrete via urine

25

What genetic mutation causes sickle cell anaemia?

Substitution in codon 6 of beta gene in chromosome 9

Glutamine to valine

26

What type of haemoglobin is produced in sickle cell disease?

HbS

crap structure, crap shape, 'polymerised', damages the cell membrane

27

What happens if you have a heterozygous sickle cell mutation?

Sickle cell trait

Most likely asymptomatic but you can pass the gene on

28

What is the mode of inheritance of sickle cell anaemia?

Autosomal recessive

29

Sickle cells have a shortened ___ ___.

What process does this cause?

shortened life span

haemolysis

30

What is an acute problem seen in sickle cell anaemia?

Infarctions caused by sickle cells occluding circulation - sickle cell crisis

Can affect spleen causing hyposplenism