Hemoglobinopathies
Terms
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- Name the 3 major Hemoglobins that are present in mature red blood cells
- Hemoglobin A(98%), A2, and F
- How do the various Hemoglobins differ and how are they similar?
- They all share globin chain alpha but differ in the second globin chain.
- What feature allows Hb F to cross the placenta?
- It's affinity for oxygen.
- When does rbc production begin in the embryo?
- By day 19 in the yolk sac.
- What are the forms of embryonic Hb? & What how do they fxn after birth?
- Gower 1, Gower 2, and Portland. These Hb's are of no clinical importance after birth.
- These are defined as mutations that affect the production of normal Hb chains
- Thalessemia syndromes
- What are 4 major genetic abnormalities that can occur in globin synthesis?
-
1. Decreased solubility
2. Oxygen Transport (w/ high/low O2 affinity)
3. Oxygen reduction status
4. Monomeric state - Why do most of the hemoglobinopathies affect the beta chain?
- Because there are 4 copies of the alpha chain.
- Name the 4 types of hemoglobinopathies studied?
-
1) sickle cell syndromes
2) unstable Hb's
3) Hb's w/ altered O2 affinity
4) Hb M - What are some promoters of rbc cell sickling?
- hypoxia, low pH, 2,3DPG, reduced rbc H2O, and fever
- Name two tests for sickle cell syndrome?
-
1) sickle prep test w/ dithionate or metabisulfate
2) Hb electrophoresis - This is the dominant cause of morbidity and mortality in HbSS (sickle cell anemia)
- vasocclusive crisis
- What is splenic sequestration crisis?
- the spleen enlarges in kids and Hb drops; the child bleeds into the spleen
- Aplastic crisis
- Is due to Parvovirus B19 or secondary folic acid deficiency; occurs when rbc production turns off