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Hemoglobinopathies 2


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What is the normal Hb distrib in a healthy adult?
HbA = 97%
HbA2 = 2%
HbF = 1%
What percentage can HbA2 never be?
more than 7-10% - there's just not that many delta chains.
What is the definition of Hbopathy?
Condition where Hb synthesis is abnormal; Either inherited or genetic mutations.
Result = structural instability or nonfunction of Hb molecule.
What are 5 ways of having a Hbopathy condition?
1. Single or double AminoAcid substitution.
2. Amino acid deletion
3. Decr. Hb chain production
4. Cross-linked or fused Hb
5. Longated subunits
What are the formal names of
-Decr. Hb chain production
-Cross-linked or fused Hb
-Longated subunits
-Hb Lepore
-Hb Constant Spring
What are the 2 types of Hb electrophoresis?
Cellulose acetate, pH = 8.4

Citrate gel, pH = 6.2
What is the sequence of migration of Hb in alkaline medium? (moving toward pos)
Can santa fly away before halloween?
What is the sequence of migration of Hb in acid medium?
(moving toward positive, so opposite direction of Alk)
Fast As She Can
What bands do you seen for Normal patients on
Alk: Majority is A, small amt A2 on the C band

Acid: All is A
What bands are seen for a ptnt with Sickle cell Disease?
Alk: majority at S, some A2 and F

Acid: majority is S, some F
what is the Hb pattern in S trait?
Alk: 60% A, 40% S -> biggest bands are A and S, some at C for A2.
Acid: Smaller A band, most S.
what type of inheritance pattern of sickle cell disease and trait?
Autosomal co-dominant inheritnc
Disease = homozygous
Trait = heterozygous
What chromosomes are the Hb genes on?
11 and 16
What Hb genes are on
-Chromosome 11
-Chromosome 16
11: 1 Beta, 2 Gamma, 1 epsilon, 1 delta.

16: 2 zeta, 2 epsilon
what gene/s is/are altered in sickle cell anemia?
the beta gene on chrom 11
why is there a 60/40 ratio of normal to abnormal Hb in Sickle cell trait?
Why doesn't Disease?
because normal has a higher Hb affinity

b/c all the Hb in disease is HbS and there are no normal B chains.
What occurs in Sickling phenom?
1. Due to decreased O2 affinity, deoxygenation -> incr. viscosity
2. RBCs less pliable; plug up circulation.
3. Plug causes more deoxygen.
4. Tactoid bars form - 15 Hb molecules per bar.
5. Tactoid bars sickle cells and block vessels.
6. Ischemic infarct results
7. Result: pain, tissue death
What is a thrombotic sickle crisis?
an Aplastic crisis due to viral infections (they change pH), causing hemolysis of the sickled cells.
What is the occurence of SS dis?
Worldwide is 1/500

U.s. is 1/1875 Afric.Americans
what causes sickling to be irreversible?

How does sickling alter lifespan of RBC?
if cells are sickled 7 to 8 x.

Life = 14-17 days inst. of 120
What are 5 clinical features of SS disease?
1. Fatigue, jaundice, leg ulcer
2. Autosplenectomy
3. Joint pain
4. Aplastic crisis
5. sickling crisis - bact. inf
What are the 4 major lab findings in SS disease?
1. Severe hemolytic N/N anemia
2. Aniso/poik
3. Erythroid hyperplasia
4. Evidence of free Hb and Red cell destruction
Waht are 5 steps in diagnosing SS disease?
1. Physical symptoms/PBS
2. Hb Solubility test
3. Urea solubility test
4. Hb Electrophoresis - BEST
5. Sickle cell prep
what is the normal electroph pattern of a 6 mo old or younger?
Some HbA but still a lot of HbF - it is the FETAL Hb.
What 6 ways can one treat SS disease?
1. Administer O2 - prevent sckl
2. Hydroxyurea
3. Transfuse - esp infants.
4. Support - iron chelate/pain
5. Prevent sickling inducement
6. Bone marrow transplant - only cure
What happens w/ the iron in SS disease patients?
They get hemociderosis -> iron overload b/c they're not using it.
What are some complications of SS disease, sickle cell anemia?
1. Adapt to Anemia -> it's hard on the heart and decr. lifespan.
2. Crisis causes organ failure, thrombosis/hemorrhage, and death.
in what population is sickle cell trait found?
9% of Afr. Americans
Asian indians, Turks, Arabs, Greeks, Italians.
Malarial belt
What are the clinical features of SS trait - how does it compare anemia-wise to SS dis?
Asymptomatic and benign, with rare crises.

Not detected unless screen for HbS.
What type of patient alterations does SS trait cause?
-Wil have a Normal lifespan.
-May have a few sickle crises.
What does the PBS show in SS trait?
What other lab tests diagnose?
-Moderate target cells
-Solubility test positive
-60% A1, 40% S, 3% HbA2
What type of inheritance pattern is seen in HbC disease?

What's an interesting feature?
Non-sex linked Incomplete dominant.

Male:Female is 3:1
What nationalities is HbC disease seen in most?
Afr.Americans - 2,3%

Native W. Africans - 20-30%
How does HbC disease anemia compare to HbS?
It's less common
Milder anemia, but might have marked splenomegaly.
Why does splenomegaly develop in HbC disease?
HbC crystals are made, and the spleen attempts to keep them.
What lab information indicates HbC disease?
PBS: N/N mild anemia
Mkd Target cells, Spherocytes, Folded cells, HbC crystals.
What is necessary for forming HbC crystals?

What causes it?
40% HbC in the cell.

caused by Dehydration
What is the electroph. pattern of Hb C disease?
90% HbC
8-10% HbF
No HbA2
HAVE TO USE ACID to seperate the C from EAO on alkaline.
What is the treatment/therapy for HbC disease?
-Know the limitations - prevent dehydration, excess heat/vomit.
-Careful in pregnancy/stress.
Relatively normal lifespan.
What are te lab findings of HbC trait?
What type of anemia?
Benign anemia, maybe absent.
Mkd Targets
What is the electroph pattern of HbC trait?
35-45% HbC
55-65 HbA1 (higher affinity)
<1% HbF
Regarding Hb SC disease:
-How common?
-Anemia severity?
-3 clinical features/problems
As common as HbS disease
Mild anemia, less severe than HbC disease
1. Hemolytic Crisis
2. Splenomegaly
3. Pregnancy problems
What are lab findings in HbSC disease?
-Bone marrow
PBS shows MARKED Targets
FEW sickles, SC crystals
-polychromasia and nRBCs.
BM: hyperplasia
what's the electroph pattern of Hb SC disease?
-Half/half HbS & HbC
-maybe a little HbF
-make sure to do acid so C seperates out.
what Hbopathy/Thalassemia combos should you know about?
HbS/Beta thal
HbS/Alpha thal

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