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M2M Unit II > Hemoglobinopathies > Flashcards

Hemoglobinopathies Flashcards

1
Q

defective globin switching

A

persistence of fetal hemoglobin

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2
Q

microcytosis

A

small cells

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3
Q

hydrops fetalis

A

fetal death due to complete lack of alpha hemoglobin genes

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4
Q

What is the embryonic hemoglobin?

A

HbG

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4
Q

The tense hemoglobin state is the ______ state, while the relaxed state is _______ and planar.

A

deoxygenated; oxygen-bound

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5
Q

Where are most structural hemoglobin variants found?

A

in the Beta-globin chain

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5
Q

hemoglobin H disease

A

severe anemia because only 1/4 alpha globin gene is functional

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6
Q

What is non-covalently linked in between the globins?

A

iron and a heme group

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6
Q

How many genetic variants of hemoglobin are known?

A

600

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7
Q

What is the fetal hemoglobin?

A

HbF (alpha 2 gamma 2)

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8
Q

How do you test for sickle cell?

A

1) DNA sequencing with PCR or electrophoresis 2) southern blot

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8
Q

Thalassemia minor

A

mild phenotype; doesn’t req transfusions

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9
Q

In beta-thalassemia, defects are seen _____.

A

postnatally only

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10
Q

How are hemoglobin C and hemoglobin S different?

A

Same codon, different mutations, different phenotypes

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11
Q

HbKemsey has _____ O2 binding while hemoglobin Kansas has ______ O2 binding.

A

too tight; too weak

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12
Q

Which form of hemoglobin is the best oxygen carrier?

A

alpha-beta

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13
Q

Where is hemoglobin synthesized?

A

in the bone marrow

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14
Q

How many copies of the beta globin gene are there?

A

1

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14
Q

What is the major adult hemoglobin?

A

HbA

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14
Q

In HbKempsey, the O2 binding affinity is _____, so _____ O2 is delivered to the tissues, and to compensate, red blood cells are ________. This condition is called _______.

A

higher; less; overproduced; polycythemia

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16
Q

The 5’-3’ ____ order of genes within each cluster coincides with the _____ order of their expression during development.

A

spatial; temporal

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17
Q

structural variants/qualitative hemoglobinopathies

A

mutations that alter the globin’s properties without affecting its synthesis

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18
Q

Phenotypically, having 2 out of the 4 alpha globin genes results in _____.

A

mild anemia

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19
Q

How many oxygens does each globin bind?

A

one each; 4 per molecule

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19
hypochromia
pale blood cells
20
What is hereditary persistence of fetal hemoglobin?
benign conditions that impair the perinatal switch from gamma to beta globin synthesis (high GbF in adults)
21
Beta-thalassemia is most often caused by \_\_\_\_\_\_\_.
point mutations in the beta-globin gene
22
Alpha-thalassemia is a ______ of alpha-globin and an excess of \_\_\_\_\_.
low or no amount; beta and gamma
23
thalassemia major
beta-zero; no beta proteins being produced
24
How many identical copies of the alpha globin gene are there on each chromosome?
2
25
What does the alpha cluster encode?
zeta- alpha2- alpha1
26
Where is embryonic hemoglobin made?
in the yolk sac
27
What do structural variants of hemoglobin do?
alter O2 binding
29
What does the beta cluster encode?
epsilon- gamma G-gamma A- delta- beta
31
Why is delta hemoglobin transcribed less?
it has a weaker promoter
32
thalassemias
low to no synthesis of one globin chain
33
What is globin switching?
transitioning between hemoglobins as development progresses
34
What kind of globin is expressed in fetal development?
gamma
36
What are the 3 genetic disorders of hemoglobin?
1) structural variants 2) thalassemias 3) defective globin switching
37
What is a pseudogene?
a gene that doesn't make a protein
39
Why does globin switching occur?
HbF in fetal blood is better suited to bind O2 at the placenta than HbA (lower pO2), which binds O2 better in the lung (higher pO2)
40
hemolysis
destruction of blood cells
41
Where is fetal hemoglobin made?
in the liver
42
Why is beta globin often affected by mutations?
there are only 2 copies of it, not 4 like alpha
43
Complex beta-thalassemia is caused by \_\_\_\_.
large deletions
44
In sickle cell anemia, a glutamate at position 6 is changed to \_\_\_\_\_\_, which changes the position that Mst II cleaves at, making a ______ protein than the wildtype.
valine; larger
45
What is the minor form of adult hemoglobin?
HbA2 (alpha 2 delta 2)
46
What is the solubility of hemoglobin S?
normal when oxygen is bound, but only 20% of normal when unbound
47
What happens when the LCR is knocked out of the beta cluster?
beta thalassemias result and alpha-globin chains precipitate
48
Alpha-thalassemia is occasionally caused by \_\_\_\_\_\_\_.
deletions in the LCR or the beta-gene cluster
49
In HbKansas, the O2 binding affinity is \_\_\_\_\_, so _____ O2 is delivered to the tissues, and ______ occurs.
decreased; less; cyanosis
50
Alpha-thalassemia is caused by \_\_\_\_\_\_\_.
a deletion of the alpha-globin gene(s)
52
Where is the alpha globin gene cluster located?
chromosome 16
54
Which is the first globin expressed?
epsilon
55
What does LCR stand for?
locus control region
56
Beta-thalassemia is a ______ of beta-globin and an excess of \_\_\_\_\_\_\_\_.
low or no amount; alpha-globin
57
Hemoglobin is a tetramer of 2 _____ polypeptides and 2 _____ polypeptides.
alpha; beta
58
What is the LCR of hemoglobin?
the promoter region about 20kb away from the first hemoglobin gene that regulates sequential transcription of all the genes
59
In alpha-thalassemia, defects are seen \_\_\_\_\_.
fetally and postnatally
60
Where is the beta globin gene cluster located?
chromosome 11

M2M Unit II (21 decks)

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