Haemoglobinopathy Flashcards Preview

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Flashcards in Haemoglobinopathy Deck (44)
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1

Describe the structure of haemoglobin

2 alpha and 2 beta chains

One haem group attached to each

2

What are the 3 major forms of Hb?

HbA (2 alpha and 2 beta)

HbA2 (2 alpha ad 2 delta)

HbF (fetal haemoglobin)

3

Alpha and beta genes are on which chromosomes?

Alpha gene is on chromosome 16

Beta gene is on chromosome 11

4

How many alpha and beta genes are there per chromosome and cell?

2 alpha genes per chromosome - 4 per cell

1 beta gene per chromosome - 2 per cell

5

When are adult levels of haemoglobin reached in infancy?

At 6-12 months

Before this HbF predominates

6

Are hereditary conditions affecting globing chain synthesis usually autosomal recessive or autosomal dominant?

Usually autosomal recessive

7

What are the 2 main groups of haemoglobinopathy?

Thalassaemias
(Decreased rate of globin chain synthesis)

Structural haemoglobin variants
(normal production of structurally abnormal globin chains)

8

What investigations can be done for haemoglobinopathies?

Genetic screening

FBCs and Hb

HPLC (high performance liquid chromatography)

9

What is HPLC (high performance liquid chromatography)? What would it show in alpha vs beta that trait?

A test for haemoglobinopathies which involves identifying and quantifying haemoglobins that are present

HPLC is normal in alpha that trait so DNA testing is required

HPLC shows raised HbA2 in beta that trait

10

Thalassaemias cause what type of anaemia?

Microcytic hypochromic anaemia

11

What types of Hb are affected in patients with alpha thalassaemia?

Alpha chains are present in all forms of Hb, therefore HbA, HbA2 and HbF are all affected

12

What is the genetic problem in alpha that trait?

There are 1-2 alpha genes missing

13

What is the genetic problem in HbH disease?

There is only 1 functional alpha gene

There are not enough alpha chains, so excess B chains form tetramers called HbH which can't carry oxygen

14

People from which parts of the world are most likely to be affected by HbH disease?

SE Asia

Middle East

Mediterranean

15

Why does splenomegaly occur in HbH disease?

Due to extra medullar haematopoiesis

16

Why does jaundice occur in HbH disease?

Haemolysis and ineffective erythropoiesis

17

How is HbH disease managed?

There is a big clinical spectrum varying from moderate anaemia to transfusion dependent conditions

Severe cases will need splenectomy +/- transfusions

18

What is Hb barts hydrops fetalis syndrome?

Most severe form of a thalassaemia in which no a genes are inherited from either parents and there is therefore minimal or no a chain production.

HbA and HbF can't be made and thus Hb Barts and HbH form the majority of Hb at birth.

19

How does Hb barts hydrops fettles syndrome present clinically?

Sevre anaemia

Serve hepatosplenomegaly

Cardiac failure

Growth retardation and skeletal abnormalities

ALMOST ALL DIE IN UTERO

20

What is alpha thalassaemia?

Disorder of alpha chain synthesis

21

What is beta thalassamia?

Disorder of beta chain synthesis

22

What kind of mutations most commonly cause beta thalassaemia?

Point mutations

23

Which form(s) of Hb are affected in beta thalassaemia?

Only HbA is affected

24

How does B thalassaemia trait present?

Asymptomatic or mild anaemia

Low MCV, raised HbA2

25

How does B thalassamia intermedia present?

Simiar clinical picture to HbH disease

Moderate severity anaemia requiring ocasional transfusions

26

When does B thalassaemia major present?

Presents at 6-24 months as HbF falls

27

What would haemoglobin analysis show in B thalassamia major?

Mainly HbF and minimal HbA

28

How does B thalassaemia major present?

Failure to thrive

Pallor

Hepatosplenomegaly

Skeletal changes

Organ damage

Risk of cord compression

29

Regular transfusion can be performed to manage B thalassaemia major. What is the aim for the levels of Hb?

95-105g/L

30

What are the treatment options for B thalassaemia major?

Regular transfusion

Bone marrow transplant (if carried out before complications develop)