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Haematology > Haemaglobinopathies and sickle cell > Flashcards

Haemaglobinopathies and sickle cell Flashcards

1
Q

what is the problem in haemoglobinopathies

A

problems with globin chains

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2
Q

HbA2 has 2 alpha chains and 2 ____ chains

A

delta

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3
Q

HbA has 2 alpha chains and 2 _______ chains

A

beta

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4
Q

alpha like genes are on chromosome ___

A

16

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5
Q

beta like genes are on chromosome ___

A

11

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6
Q

adult levels of Hb reached by what age?

A

6-9 months

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7
Q

when does beta chain production kind of start

A

few months after birth

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8
Q

what are haemoglobinopathies

A

hereditary conditions affecting globin chain synthesis

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9
Q

two main groups of

A
  • thalassaemias
  • structural haemoglobin variants
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10
Q

thalassaemias

A

mutation resulted in you not producing enough of the globin chains

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11
Q

structural haemoglobin variants

A

normal production of abnormal globin chain

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12
Q

alpha thalassaemia

A

not making enough alpha globin chains

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13
Q

beta thalassaemia

A

not making enough beta globin chains

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14
Q

consequences of thalassaemias

A

inadequate Hb production —> microcytic hypochromic anaemia

If severe:
- Unbalanced accumulation of globin chains which are toxic to the cell
- Ineffective erythropoiesis
- Haemolysis

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15
Q

what does alpha thalassaemia result from?

A

results from deletion of one or both alpha genes from chromosome 16

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16
Q

alpha thalassaemia trait

A

missing one or two alpha genes

Microcytic, hypochromic red cells with mild anaemia

asymptomatic

don’t need treatment
carrier state

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17
Q

HbH disease

A

a form of alpha thalassaemia.
only one working alpha gene per cell - moderate to severe anaemia

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18
Q

Hb Barts hydrops fetalis

A

no functional α genes (–/–) incompatible with life

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19
Q

HbH disease signs symptoms

A

jaundice, splenomegaly

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20
Q

what is the most severe form of alpha thalassaemia

A

Hb Barts Hydrops Foetalis Syndrome

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21
Q

How can alpha thalassaemia trait be distinguished from iron deficiency?

A

ferritin will be normal in alpha thalassaemia trait

22
Q

beta thalassaemia is usually caused by ______ mutations within the beta gene

A

point

23
Q

alpha thalassaemia is usually to do with ________ of alpha genes

A

deletion

24
Q

classification of beta thalassaemia

A

beta thalassaemia trait

beta thalassaemia intermedia

beta thalassaemia major

25
Q

beta thalassaemia trait diagnosis

A

increased HbA2

26
Q

beta thalassaemia trait

A

asymptomatic

27
Q

do beta thalassaemia intermedia patients need transfusion?

A

require occasional blood transfusion

28
Q

beta thalassaemia major when does it present

A

6-24 months (as HbF falls)

29
Q

beta thalassaemia major symptoms

A

pallor, failure to thrive

30
Q

beta thalassaemia major - extramedullary haematopoiesis complications:

A
  • hepatosplenomegaly
  • skeletal changes
  • organ damage
31
Q

beta thalassaemia major haemoglobin analysis

A
  • mainly HbF
  • no HbA (or possibly a little bit)
32
Q

management of beta thalassaemia major

A

Regular transfusion programme to maintain Hb at 95-105g/l

Bone marrow transplant may be an option if carried out before complications develop

33
Q

blood transfusions for management of beta thalassaemia major - what is the main cause of mortality

A

iron overload from transfusion

34
Q

consequences of iron overload - endocrine dysfunction

A

Impaired growth and pubertal development
Diabetes
Osteoporosis

35
Q

consequences of iron overload - cardiac disease

A

Cardiomyopathy
Arrhythmias

36
Q

consequences of iron overload - liver disease

A

Cirrhosis
Hepatocellular cancer

37
Q

management of iron overload

A

iron chelating drugs (e.g. desferrioxamine)

38
Q

transfusion related complications

A

Viral infection - HIV, Hepatitis B and C
Alloantibodies – hard to crossmatch
Transfusion reactions

39
Q

what cause sickle cell

A

point mutation in codon of the beta globin gene
(so altered beta chain ‘beta S’)

40
Q

HbAS

A

sickle cell trait
asymptomatic carrier state
mainly HbA, HbS <50%

41
Q

HbSS

A

sickle cell anaemia
HbS >80%, no HbA

42
Q

sickle cell anaemia genes

A

two abnormal beta genes

43
Q

what is sickle crisis

A

episodes of tissue infarction due to vascular occlusion

symptoms depend on site and severity

pain may be extremely severe

44
Q

sickle crisis consequences

A

tissue ischaemia and pain

45
Q

precipitants of sickle crisis

A
  • hypoxia
  • dehydration
  • infection
  • cold exposure
  • stress/fatigue
46
Q

sickle crisis treatment

A

medical emergency

  • opiate analgesia
  • hydration (IV fluids)
  • rest
  • oxygen
  • antibiotics if evidence of infection

if life-threatening (if sickling is happening in lungs or brain) - red cell exchange transfusion

47
Q

when would red cell exchange transfusion be used in the treatment of sickle crisis

A

severe crisis eg (lung) chest crisis or (brain)stroke to rapidly reduce proportion of HbS in blood

48
Q

longterm management of sickle

A

Hyposplenism - reduce risk of infection:
- prophylactic penicillin
- vaccination; pneumococcus, meningococcus, haemophilus

Folic acid supplementation (↑ RBC turnover so ↑demand)

Hydroxycarbamide can reduce severity of disease by inducing HbF production

Regular transfusion to prevent stroke in selected cases

49
Q

haemoglobinopathy diagnosis - simple first things

A
  • FBC; Hb, red cell indices
  • Blood film
  • Ethnic origin
50
Q

haemoglobinopathy diagnosis - high performance liquid chromatography or electrophoresis what are these tests for

A

to quantify haemoglobins present
Identifies abnormal haemoglobins eg HbS
Raised HbA2 diagnostic of beta thal trait

51
Q

screening for haemoglobinopathies

A

antenatal to identify carrier parents now standard

family origin questionnaire and FBC

further testing if from high risk area or abnormal RBC indices

newborn screening programme also in place

52
Q

thalassaemia trait is believed to confer some protection against _________ __________

A

falciparum malaria

Haematology (36 decks)

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