Haemaglobinopathies Flashcards

(38 cards)

1
Q

disorders of haemoglobin usually inherited as?

A

autosomal recessive

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2
Q

adult haemoglobin made up of 3 things:

A

2 a chains
2 B-chains
4 iron

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3
Q

normal adult haemoglobin protein is what kind of protein?

A

heterotetramer: 2:2 a:B

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4
Q

a-chain found on which chromosome?

A

16

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5
Q

B-chains found on which chromosome?

A

11

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6
Q

where are the y-chains found? what purpose?

A
  1. found on chromosome 11 with B-chains

2. part of fetal haemoglobin

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7
Q

fetal haemoglobin tetrameter consists of? adult?

A

fetal: a2y2
adult: a2B2

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8
Q

what happens in a or B thalassaemias?

A

decreased synthesis of one or more globins = imbalance

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9
Q

structural variants of haemoglobin means what? eg.?

A

different shape, not different rate of synthesis

eg. sickle cell disease

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10
Q

what is hereditary persistance of fetal haemoglobin?

A

benign condition, more fetal haemoglobin as adult

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11
Q

what is HbE?

A

mild thalassaemia phenotype

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12
Q

in thalassaemias, what are the haemoglobin proteins structure like?

A

homotetramers = imbalance

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13
Q

how to homotetramers cause pathology?

A

insoluble in RBCs, non-functional, accumulate and damage RBCs = haemolytic anaemia

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14
Q

a-thalassaemias cause usually?

A

large deletions

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15
Q

B-thalassaemias cause usually?

A
point mutations
-promotor
RNA splicing
nonsense
frameshift
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16
Q

what is B+ and Bo conditions:

A

B+ =some haemoglobin made

Bo = no haemoglobin whatsoever

17
Q

what do RBCs look like in B-thalassaemia homozygous?

A

microcytic

hypochromomic

18
Q

what happens to iron in B-thalassaemia

A

systemic iron overload

19
Q

consequences of bone marrow not being able to supply RBC demands?

A

marrow expansion and extramedullary erythropoiesis

20
Q

what happens to spleen in B-thalassaemia?

A

splenomegaly from filtering out the defective RBCs and the extramedullary erythropoieseis

21
Q

why are there tear-drop shaped cells in B-thalassaemia?

A

a4 aggregate inclusions on one side of cell

22
Q

what kind of cells in B-thalassaemia on slide?

A
teardrop
microcytic
hypochromic
target cells
anisocytotic
23
Q

changes to blood parameter for heterozygous B-thalassaemia?

A

minor decreased/elevations, asymptomatic

24
Q

problem with blood transfusions in B-thalassaemia?

A

exaccerbate the iron overload, need chelation

25
only known cure for B-thalassaemia?
bone marrow transplant
26
why HRT for B-thalassaemia?
girls get menopause at 15 due to iron complications
27
with alpha-thalassaemia, what kind of homotetramers can you get?
y4 | B4
28
how many functional genes in alpha-thalassaemia trait? two kinds?
2 a-/a- aa/--
29
in alpha-thalassaemia trait, what do we have to worry about for parents wanting to have children?
If parents both have aa/-- then risk of having HbBart (--/--) is 1 in 4
30
if both parents with alpha-thalassaemia trait have a-/a- then what are their children?
a-/a- and you get mild anaemia
31
sickle cell disease point mutation where:
glutamate >> valine
32
how does sickle cell damage RBCs?
in deoxygenated/stress states, the HbS aggregate and cause sickling of RBCs, repetitive leads to irreversible sickling and adhere to endothelium
33
sickle cells appear how on slide?
severe normocytic or macrocytic
34
what kind of anaemia in sickle cell?
haemolytic anaemia
35
how is MCV/MCH affected in heterozygous vs. homozygous sickle cell?
heterozygous: normal or reduced homozygous: normal unless in crises
36
what are compound heterozygotes?
2 kinds of mutation on the B-globin mutation, HbS or HbE?
37
what are double heterozygotes?
B and a globin mutation. (actually do better, less imbalance)
38
future therapies of thalassaemias?
gene therapy