Thalassemias (DiPaola L1) Flashcards

0
Q

Which Hb genes are primarilly expressed as a fetus? (week 6 - birth)

Where are the Hb produced during fetal life?

A

alpha
gamma (beta-like)
HbF
Liver–> Spleen–> Bone Marrow

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1
Q

Which hemoglobin genes are expressed in the first few weeks of life? (0 - 6 wks)
Where is is produced?

A

Epsilon (beta-like)
Zeta (alpha-like)
–> Gower 1, Gower 2, Portland
yolk salk

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2
Q

Which Hb genes are primarily expressed after birth?
Where is this Hb produced?

Which Hb is expressed in small amounts after birth?

A

Primarily
alpha & beta
Bone Marrow

small amts: gamma

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3
Q

What does the delta (beta-like) Hb gene do?

A

produced in very small amts as an adult
likely a evolutionary remnant
HbA_2

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4
Q

What are the structural hemoglobinopathies?

What sort of mutations cause these?

A

Point mutations
HbS Glu6Val
HbC Glu6Lys
HbE Glu26Lys

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5
Q

HbS

loss of function? gain? etc?

A

Novel Function

polymerization of the Hb molecules

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6
Q

What is the histological change that you see in HbC?

What is the clinical presentation?

A

Crystalization of the hemoglobin in a blood smear.
Can get more infections (give penicillin)

often called HbC trait b/c no other symptoms

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7
Q

According to the formal definition of Thalassemia, what is the problem?

A

reduced rate of production of one or more chains of Hb.
** abnormal ratio of Hb chain production
defective Hb production & damage to the red blood cells and their precursors

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8
Q

What deletion causes HbH?

A

3-gene deletion of Hb alpha

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9
Q

What deletion(s) cause alpha thalassemia trait?

A

alpha-thal 1: deletion of both alphas on one homologue

alpha-thal 2: deletion of one alpha on each homologue

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10
Q

Which alpha hemoglobin gene deletion is clinically insignificant?

A

if only one of the 4 alpha genes is deleted.

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11
Q

What is Gamma thalassemia?

A

clinically significant only at birth; no longer a problem at about 6 months of age.
Gamma Hb is a beta-like Hb so eventually beta proper will take over and the gamma deletion is not a problem.

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12
Q

What is delta thalassemia?

A

By itself is not a problem because delta is a beta-like hb so beta will take over anyway.

if, however you have a delta-beta deletion, now its a problem.

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13
Q

What are normal Hb levels?

A
all units are gm/dL
Newborns:  17-22
1 week: 15-20
1 month: 11-15
children: 11-13
adult male: 14-18
adult female: 12-16
geriatric male: 12.4 - 14.9
geriatric female: 11.7 - 13.8

So basically if you have in the single digits its Low, upper teens (dep on gender) or higher is High

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14
Q

What is the reticulocyte count and a normal value?

A

immature red blood cells
blood levels should be low 1-3%

0 is bad and higher levels indicate lots of red blood cell production

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15
Q

What is microcytic and what lab values would indicate this?

A

low red blood cell counts
MCV (mean corpuscular volume) should be around
76 - 100 fL

16
Q

What is Cooleys anemia?

A

beta-thal major
2 severely abnormal or absent beta genes
severe anemia, low MCV count, transfusion dependent
x-ray shows dense marrow expansion in the skull bone changes b/c making marrow in as much bone as you can –> fractures
enlarged spleen & liver
iron overload- body absorbs more b/c trying to make more blood cells

17
Q

If a pt. is transfusion dependent, what sort of other treatments are indicated?

A

iron chelation
vitamin C (assists in chelation)
spelenectomy / cholecystectomy
bone marrow transplant

18
Q

What does the RDW in a CBC tell you and what are normal values?

A

RDW = red cell distribution width
variability in the size of red blood cells
normal variation values: 11.5 - 14.5%