Heme Flashcards
What is MCV and what is the normal value?
MCV = mean corpuscular volume
MCV is the size of RBCs
Normal value is 80%
Elevated MCV is suggestive of
Nothing
Decreased MCV is suggestive of
hemoglobinopathy or iron deficiency
What is MCH?
MCH = mean corpuscular hemoglobin
MCH is the amount of hemoglobin in RBC based on size
What is HbA and what is its composition?
normal adult hemoglobin (constitutes 95-98% of hemoglobin in healthy adults)
composed of two alpha and two beta chains
What is HbA2 and what is its composition?
minor component of adult hemoglobin (2-3% of hemoglobin in healthy adults)
composed of two alpha and two delta chains
Elevated HbA2 can be indicative of
beta-thal
What is HbF and what is its composition?
fetal hemoglobin (predominant in fetuses and newborns but is < 1-2% of hemoglobin in adults)
composed of two alpha and two gamma chains
Elevated HbF can be indicative of
sickle cell and beta-thal
What is HbE and what is its cause?
an abnormal hemoglobin variant resulting from a mutation in the beta globin gene
HbE is common in which population?
Southeast Asian descent
When present in homozygous form, HbE can lead to:
mild anemia
What is HbS and what is its cause?
sickle hemoglobin resulting from a mutation in the beta globin gene
What is HbC and what is its cause?
an abnormal hemoglobin variant results from a mutation in the beta globin gene
HbC is common in which population?
West African descent
HbC can be associated with what health condition?
Mild hemolytic anemia
What is the most common single gene disorder in humans?
hemoglobinopathies
What is an example of a qualitative hemoglobinopathy?
structural Hb variants like sickle cell anemia
What is an example of a quantitative hemoglobinopathy?
thalassemias
Single cell anemia or HbSS is caused by which point mutation in which gene?
Glu6Val missense point mutation in HBB gene
What is the inheritance pattern of sickle cell anemia?
AR
Symptoms of sickle cell anemia
-painful swelling of hands and feet
-jaundice
-hemolytic anemia -> fatigue
-pain crises and organ damage due to blockages caused by sickled RBCs clumping
Sickle hemoglobin-C disease or HbSC is caused by which point mutation in which gene?
Glu6Lys missense point mutation in HBB gene
(Lys = “less” bad form of sickle cell)
Crystal-like structures on a blood smear are associated with which variant of hemoglobin?
HbC
(C = crystals)
Sickle beta-thalassemia or HbSB-thal is caused by mutations in
one sickle cell gene and one beta-thal gene
(Glu6Val + B thal mutation)
Two types of B thal mutations in HbSB-thal
B+ = present, but reduced amount of normal hemoglobin
B0 = no normal hemoglobin
Which B thal mutation causes a less severe phenotype in HbSB-thal (B+ or B0)?
B0 has less frequent pain crises and less likely to develop stroke or pulmonary hypertension
blood smear findings for an individual with HbAS
normal blood smear
Treatment for an acute crisis in sickle cell anemia
fluids, oxygen, analgesics, transfusions (and medications that induce HbF production)
Treatment for sickle cell anemia (not necessarily during an acute crisis)
-hydroxyurea to increase HbF production
-immunizations
-penicillin
-bone marrow transplant
Thalassemias are caused by mutations in genes that produce
hemoglobin chains (alpha or beta chains)
