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3 Haematology > Haemoglobinopathy > Flashcards

Haemoglobinopathy Flashcards

1
Q

HbA2 is made up of what chains?

A

2 alpha 2 delta

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2
Q

main form of Hb

A

HbA (2 alpha 2 beta)

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3
Q

alpha like genes are found on what chromosome?

A

16

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4
Q

beta like genes are found on what chromosome?

A

11

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5
Q

when are adult levels of Hb reached after birth?

A

6-12 months

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6
Q

how does fetal Hb become adult Hb?

A

gamma chains switched off, beta chains switched on and replace it

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7
Q

what are haemoglobinopathies?

A

hereditary conditions affecting the globin chain

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8
Q

what happens in thalassaemia?

A

make a globin chain but not ENOUGH of it because of decreased rate of globin chain synthesis

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9
Q

what happens in structural Hb variants?

A

make a structurally abnormal globin chain

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10
Q

name the 2 main types of h-opathy

A

thalassaemia

structural Hb variants

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11
Q

2 types of thalassaemia

A

alpha and beta (depending on which chains are affected)

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12
Q

what anaemia is caused from thalassaemia and why?

A

microcytic hypochromic anaemia because of inadequate Hb production from lack of or ineffective globin

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13
Q

why do you get haemolysis and ineffective erythropoesis in thalassaemia?

A

unbalanced accumulation of globin chains is toxic

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14
Q

thalassaemia is mono/polygenic

A

mono

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15
Q

normally have _ alpha genes per cell, _ from each parent

A

4

2

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16
Q

normally have _ beta genes per cell, _

from each parent

A

2

1

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17
Q

what types of Hb are affected in alpha thalassaemia?

A

all of them as they all contain alpha chains

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18
Q

what happens when you lose all your alpha genes?

A

hydrops fetalis

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19
Q

what is HbH disease?

A

only 1 functional alpha chain out of 4

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20
Q

how many genes are lost to give you alpha thalassaemia trait?

A

one or two

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21
Q

symptoms of alpha thalassaemia trait

A

asymptomatic

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22
Q

describe a film of alpha thal trait

A

microcytic, hypochromic red cells

mild anaemia

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23
Q

how can you differentiate alpha thal trait from ID anaemia?

A

ferritin is normal in ATT

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24
Q

describe a blood film of HbH disease

A

anaemia
VERY low MCV
MCH

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25
Q

what is HbH

A

tetramers formed by excess B chains in the presence of alpha thalassaemia

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26
Q

clinical presentation of HbH

A

SE asian patient
moderate-severe anaemia
splenomegaly
jaundice from haemolysis/ineffective erythopoesis

27
Q

why do patients with thalassaemias get splenomegaly sometimes?

A

undergo extramedullary haematopoesis as bone marrow cant make RBCs

28
Q

clinical features of hydrops fetalis

A 
severe anaemia
cardiac failure
growth retardation
severe hepatosplenomegaly
skeletal problems
death in utero
29
Q

blood film of hydrops fetalis?

A

nucleated RBCs in peripheral blood

30
Q

genetic cause of beta thal?

A

point mutation

31
Q

what Hb type is affected in beta thal?

A

HbA

32
Q

name the 3 types of beta thal

A

b thal trait
b thal intermedia
b thal major

33
Q

symptoms of b thal trait

A

asymptomatic
no/mild anaemia
low MCV/MCH

34
Q

what Hb type is raised in b thal trait

A

raised HbA2

35
Q

which type(s) of b thal is/are transfusion dependent

A

b thal major

36
Q

when does b thal major present? why?

A

6-24 months

HbF falls and HbB should take over

37
Q

clinical presentation of b thal major

A 
pallor
failure to thrive
hepatosplenomegaly
skeletal changes
organ damage
(from extramedullary haematopoesis)
38
Q

what Hb types are most prominent in b thal major?

A

HbF mainly

minimal HbA

39
Q

complication of extramedullary haematopoesis

A

cord compression

40
Q

Tx b thal major

A

transfusion- Hb 95-105g/l

BM transplant

41
Q

main complication of transfusion in b thal major

A

iron overload

42
Q

consequences of iron overload in thalassaemia?

A

endocrine- impaired growth/diabetes/osteo
cardiac disease - arrhythmias/myopathy
liver - cirrhosis/hepatocellular cancer

43
Q

Tx iron overload

A

iron chelating drug eg desferrioxamine

keep iron to 250mg per unit of red cells in transfusions

44
Q

what do iron chelating drugs do?

A

bind to iron to create a complex that allows it to be excreted

45
Q

genetic cause of sickle cell? what substance is affected?

A

point mutation in the B globin gene

produces substance called “beta S”

46
Q

what is the Hb structure in sickle cell?

A

HbS (A2 BS2)

47
Q

describe the B genes in sickle trait

A

1 normal B gene

1 abnormal Bs gene

48
Q

sickle trait is asymptomatic T or F

A

T

49
Q

what Hb type is mainly in sickle trait?

A

HbA

do get HbS

50
Q

B genes present in sickle cell anaemia?

A

2 Bs genes

51
Q

inheritance of SCA

A

AR

52
Q

what types of Hb are present in SCA

A

HbS in most

NO HbA!!

53
Q

what is sickle crisis?

A

episodes of tissue infarction due to vascular occlusion by wedged sickle cells

54
Q

symptoms of sickle crisis

A

depend on site and severity

pain

55
Q

locations of sickle crisis?

A

digits, BM, lung, spleen, CNS

56
Q

why is there haemolysis in SCA?

A

RBCs have much shorter life span as they have a sickle shape

57
Q

precipitants of sickle crisis

A 
hypoxia
dehydration
infection
cold
stress/fatigue
58
Q

Tx sickle crisis

A 
opiate analgesia
hydration
rest
O2
antibiotics if infection
venesect-transfuse if severe
59
Q

why do SCA patients get hyposplenism

A

common site of infarction in sickle crisis

60
Q

long term effects of SCA

A

impaired growth

end organ damage eg pulm HT, renal disease, stroke

61
Q

long term Tx of SCA

A

prophylactic ABs for hyposplenism
folic acid supplements to inc RBC turnover
hydroxycarbamide
regular transfusion

62
Q

Ix haemoglobinopathy

A

FBC
Hb
red cell indices
liquid chromatography orgel electrophoresis to check what Hbs are present

63
Q

raised HbA2 is diagnostic of….

A

beta thal trait

3 Haematology (30 decks)

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