Most prevalent adult hemoglobin has these globin subunits:
Alpha 2 beta 2
The alternative form of adult hemoglobin has these globin subunits:
Alpha 2 delta 2
Fetal hemoglobin has _____ affinity for oxygen due to its ____ subunit
Higher
Gamma
Homotetramer of _____, Hb____, is observed with alpha-thalassemia
Beta globin (complete absence of alpha globin)
HbH – alpha-thalassemia
Alpha thalassemia observed in fetus is also known as ___
Hb Barts
Alpha globin at chromosome ___ and non-alpha globin at chromosome ____
16 (alpha)
11 (non-alpha)
T/F: fetal hemoglobin is present right at start of gestational period (day 0)
False; alpha and gamma subunits begin to form around 3 months or so
Embryonic is zeta and epsilon
Embryonic hemoglobin:
Gower 1 (zeta 2 epsilon 2)
Portland 1 (zeta 2 gamma 2)
Gower 2 (alpha 2 epsilon 2)
Epsilon globin _____ at the same rate as _____ globin increases, which then decreases at the same rate that ___ globin increases and is supplemented by _____ globin
Decreases
Gamma
Beta
Delta
Deficiency of which globin is fatal to early embryonic stage:
Epsilon
Zeta
T/F: deficiency of delta globin is usually fatal
False; it is the alternative adult hemoglobin
T/F: beta thalassemia is irrelevant prior to birth
True; neonate is completely normal at birth with beta thalassemia and continue to be okay for 4 months after until existing fetal hgb becomes depleted
Beta globin deficiency can cause insufficiency of ______ (hemoglobin tetramer), as well as an excess of ____ globin subunit
HbA1
Alpha
What happens with excess alpha globin in beta-thalassemia?
Alph globin precipitates causing damage to the RBC membrane which reduces rbc half life leading to hemolytic anemia and iron overload
Betal thalassemia minor vs beta thalassemia major:
Minor- has one working allele (B0/B) = beta-thalassemia trait
Major- has no working allele = complete knockout (B0/B0)
What is Cooley anemia?
It is beta thalassemia major – no expression of beta globin from either allele
It is severe life threatening anemia starting within months of birth
What is beta thalassemia intermedia?
Neither allele is the wildtype, but at lease some beta globin is expressed from at least one allele
HbH and Hb Barts oxygen binding ability:
Bind oxygen tightly
Lack cooperativity
Act as an oxygen sinks and are harmful
African pattern of alpha thalassemias vs Asian pattern of alpha thalassemia (alpha thal minor)
African: recombination of alpha 1 and alpha 2 genes – has one active gene at the allele
Asian: recombination of alpha 1 and psi gene- no active gene at the allele
HgH disease is alpha thalassemia _____
Intermedia
Three out of the four alpha globin genes are deleted