Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CR2 > 33 - Haemoglobinopathies > Flashcards

33 - Haemoglobinopathies Flashcards

1
Q

What is adult haemoglobin

A

2 alpha
2 beta
(Haemoglobin A)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How many genes are there for the alpha subunit

A

2
(4 genes in a normal diploid)
also a zeta gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What chromosome is the alpha subunit on

A

16

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many genes are there for the beta subunit and what are they called

A

5

Epsilon, gamma A, gamma G, delta and beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where is the first form of hb made

A

Embryonic sac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the 1st form of hb called and what is it made up of

A

Hb Gower 1
Zeta x2
Epsilon X2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What other variants of Hb can occur in the early weeks

A

Gower 2 - A2E2

Portland - Z2E2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the form of Hb that is produced after 6 weeks and what is it made up of

A

Fetal haemoglobin F
HbG
Alpha x2
Gamma x2

This replaces Hb Gower 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where is HbG produced

A

Liver and spleen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

After 3-6months of birth what replaces HbG

A

HbA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is thalassemia

A

Genetic defect resulting in inadequate quantities of one or other of the subunits that make up haemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is alpha thalassemia

A

one or more of the alpha genes on chromosome 16 is deleted/faulty

Manifested at birth
Severity depends on no of genes alleles that are defective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

One alpha gene defective

A

Alpha thalassemia minima
Minimal effect on Hb synthesis
No clinical symptoms
Slightly reduced MCV and MCHb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Two alpha genes defective

A

Alpha thalassemia Minor

Mild microcytic hypochromatic anaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Three alpha genes defective

A

Haemoglobin H disease
2 unstable Hb in blood
Microcytic hypochromatic anaemia
Higher affinity for oxygen so poor release of O2 in tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 2 abnormal hb in haemoglobin H disease

A

Hb Barts - G4

Hb H - B4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Four alpha genes defective

A

Fetus cannot live outside the uterus - stillborn
Hydrops fetalis
Little circulating Hb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the Hb that is present in thalassemia with 4 alpha genes defective

A

Hb Barts - tetrameric y chain (gamma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is beta thalassemia

A

a point mutation on chromosome 11 in Hb B gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What inheritance is B thalassemia

A

Autosomal recessive inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the difference between heterozygous and homozygous thalassemia

A

Beta thalassemia minor

Beta thalassemia major (B0 Cooley’s anaemia)

22
Q

Beta thalassemia intermedia

A

Both beta globin genes are mutated but the body can make some

23
Q

When does B thalassemia manifest

A

When switch from gamma to beta chain after birth

may be compensatory but you get an increase in HbF and A2

24
Q

What are the pathological effects of B thalassemia

A

Excess alpha globins (unstable) which precipitate on erythrocyte membrane
This causes intramedullary destruction of erythroblasts

= SEVERE HYPOCHROMATIC MICROCYTIC ANAEMIA

25
Q

What are untreated effects of B thalassemia major

A
  • Hypochromatic, microcytic anaemia
  • Bone marrow expansion, splenomegaly
  • Bone deformity, extramedullary erythropoeitic masses
  • Failure to thrive from 6 months of age
  • Pallor, short stature, facial bone abnormalities
26
Q

What are causes of B thalassemia

A

Mutation in non-coding introns
deletion of globin gene
mutation in promotor, nonsense mutation

27
Q

Treatment of thalassemia major

A

Regular transfusions
Iron chelation therapy
Splenectomy
Allogenic bone transplant

28
Q

Why do you need iron chelation therapy

A

The regular transfusions can cause iron overload

29
Q

How do you distinguish iron deficiency anaemia from thalassaemia

A

Thalassemia has normal serum iron and ferritin

30
Q

Why is excess iron a bad thing?

A

Causes excess haemolysis

Free iron can be released into the blood from haem

31
Q

What is the fenton reaction

A

If hydrogen peroxide is present
the fenton reaction occurs
hydroxyl radicals are produced = Oxidise and damage biological tissues

32
Q

What diseases are fenton reaction responsible for

A

Cirrhosis
Diabetes
glandular dysfunction

33
Q

What do iron chelating compounds do

A

Bind free iron and prevent the fenton reaction

34
Q

What are some examples of iron chelation therapies

A

Desferoxamine (desferal)
Deferiprone, Ferriprox
Desferasirox, exjade

35
Q

Desferoxamine (desferal)

A

Chelation enhanced with ascorbate

Toxicity with higher doses

36
Q

Deferiprone, Ferriprox

A

Oral iron chelator

Not to be used in pregnancy

37
Q

Deferasirox, Exjade

A

A once daily oral iron chelator

Can cause GI bleeding and kidney or liver failure

38
Q

What is sickle cell disease

A

Mutant form of Beta haemoglobin subunits -red cells to become sickle shaped

39
Q

Why are sickle shaped RBC not good

A

Obstruct capillaries and restrict blood flow

Causes ischemic pain and organ damage

40
Q

What are signs of SCD

A

Haemolytic anaemia: haemoglobin levels in the range of 6–8 g/dL
(usually 12 -17)
Large vessel damage
Microvascular occlusion

41
Q

What is the mutation in sickle hb (HbS)

A

Glutamic aid to valine (GAG-GTG)

Substitution at codon 6 of the B globin chain

42
Q

What is Haemoglobin S made up of

A 
Alpha 2 
Bs 2 (abnormal B chain)
43
Q

When does HbS distort the RBC to sickle shape

A

When the blood is deoxygenated

44
Q

Clinical consequences of SCD

A

Anaemia
Increased susceptibility to infection Vaso-occlusive crises
Chronic tissues damage

45
Q

Management of SCD

A 
Infection prophylaxis
Analgesics for painful crises 
Education, lifestyle
Transfusions 
Bone marrow transplants
46
Q

Screening

A

Blood screen

genetic councelling

47
Q

Neonatal

A

Treat with antibiotic prophylaxis
Education
Heel-prick sample

48
Q

Haemoglobin C

A

Abnormal B sub unit
Reduced plasticity and flexibility of the erythrocytes (excess haemolysis)
Hb C disease

49
Q

Haemoglobin E

A 
Abnormal Hb with single point mutation in the B chain
Inherited from both parents
Mild B-thalassemia
symptoms after 3-6 months
Mild splenomegaly
50
Q

Haemoglobin A2

A

Minor component of Hb
Found in RBC after birth (3%)
2A
2Delta

51
Q

Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency)

A 
X-linked recessive error of metabolism 
Haemolysis and jaundice  in response to triggers
Broad beans and oxidative drugs
Mediterranean - common
protected from malaria

CR2 (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions