Heme

Question 1

What is MCV and what is the normal value?

Answer 1

MCV = mean corpuscular volume
MCV is the size of RBCs
Normal value is 80%

Question 2

Elevated MCV is suggestive of

Answer 2

Nothing

Question 3

Decreased MCV is suggestive of

Answer 3

hemoglobinopathy or iron deficiency

Question 4

What is MCH?

Answer 4

MCH = mean corpuscular hemoglobin
MCH is the amount of hemoglobin in RBC based on size

Question 5

What is HbA and what is its composition?

Answer 5

normal adult hemoglobin (constitutes 95-98% of hemoglobin in healthy adults)
composed of two alpha and two beta chains

Question 6

What is HbA2 and what is its composition?

Answer 6

minor component of adult hemoglobin (2-3% of hemoglobin in healthy adults)
composed of two alpha and two delta chains

Question 7

Elevated HbA2 can be indicative of

Answer 7

beta-thal

Question 8

What is HbF and what is its composition?

Answer 8

fetal hemoglobin (predominant in fetuses and newborns but is < 1-2% of hemoglobin in adults)
composed of two alpha and two gamma chains

Question 9

Elevated HbF can be indicative of

Answer 9

sickle cell and beta-thal

Question 10

What is HbE and what is its cause?

Answer 10

an abnormal hemoglobin variant resulting from a mutation in the beta globin gene

Question 11

HbE is common in which population?

Answer 11

Southeast Asian descent

Question 12

When present in homozygous form, HbE can lead to:

Answer 12

mild anemia

Question 13

What is HbS and what is its cause?

Answer 13

sickle hemoglobin resulting from a mutation in the beta globin gene

Question 14

What is HbC and what is its cause?

Answer 14

an abnormal hemoglobin variant results from a mutation in the beta globin gene

Question 15

HbC is common in which population?

Answer 15

West African descent

Question 16

HbC can be associated with what health condition?

Answer 16

Mild hemolytic anemia

Question 17

What is the most common single gene disorder in humans?

Answer 17

hemoglobinopathies

Question 18

What is an example of a qualitative hemoglobinopathy?

Answer 18

structural Hb variants like sickle cell anemia

Question 19

What is an example of a quantitative hemoglobinopathy?

Answer 19

thalassemias

Question 20

Single cell anemia or HbSS is caused by which point mutation in which gene?

Answer 20

Glu6Val missense point mutation in HBB gene

Question 21

What is the inheritance pattern of sickle cell anemia?

Answer 21

AR

Question 22

Symptoms of sickle cell anemia

Answer 22

-painful swelling of hands and feet
-jaundice
-hemolytic anemia -> fatigue
-pain crises and organ damage due to blockages caused by sickled RBCs clumping

Question 23

Sickle hemoglobin-C disease or HbSC is caused by which point mutation in which gene?

Answer 23

Glu6Lys missense point mutation in HBB gene
(Lys = “less” bad form of sickle cell)

Question 24

Crystal-like structures on a blood smear are associated with which variant of hemoglobin?

Answer 24

HbC
(C = crystals)

Question 25

Sickle beta-thalassemia or HbSB-thal is caused by mutations in

Answer 25

one sickle cell gene and one beta-thal gene
(Glu6Val + B thal mutation)

Question 26

Two types of B thal mutations in HbSB-thal

Answer 26

B+ = present, but reduced amount of normal hemoglobin
B0 = no normal hemoglobin

Question 27

Which B thal mutation causes a less severe phenotype in HbSB-thal (B+ or B0)?

Answer 27

B0 has less frequent pain crises and less likely to develop stroke or pulmonary hypertension

Question 28

blood smear findings for an individual with HbAS

Answer 28

normal blood smear

Question 29

Treatment for an acute crisis in sickle cell anemia

Answer 29

fluids, oxygen, analgesics, transfusions (and medications that induce HbF production)

Question 30

Treatment for sickle cell anemia (not necessarily during an acute crisis)

Answer 30

-hydroxyurea to increase HbF production
-immunizations
-penicillin
-bone marrow transplant

Question 31

Thalassemias are caused by mutations in genes that produce

Answer 31

hemoglobin chains (alpha or beta chains)