Glossary of Thalassemias

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what exactly is thalassemia?
inherited cause of anemia, by decreased production of a Hb chain. Result of a gene deletion
Why is such anemia seen in thalassemia?
B/c the spleen prematurely destroys cells with precipitated chains in excess - Howell jolly bodies.
What type of anemia is a thalassemia, compared to hbopathy?
Hypo/micro, instead of normo/normo!
What are the 2 major results of Beta Thalassemia?
-Decreased Beta chains
-Compensating increase in HbA2 and HbF b/c don't have Beta.
When do you first notice Beta thalassemia? Why?
After birth, in the 1st year. B/c most Hb at birth is Fetal -> a2y2, so decreased Beta doesn't matter.
What is the Major diagnosing characteristic of Beta thal?
Decreased HbA,
Increased HbA2 and HbF
What does Bo mean?
What does B+ mean?
Bo = complete absence of Beta chains from this gene.

B+ = decreased production.
What culture is Bo most seen in?
How much Beta chain is produced from a B+ gene?
there are types 1,2,3.. in general we say about 50%
What type of gene combo causes Beta thal Major?
B+/B+ (if type 1)
what are the major symptoms of a Beta thal major?
-Severe micro/hypo anemia
-HbF like 90%, increased HbA2 and absent/none of HbA1
-Skeletal changes
What type of gene defect is intermediate B thal?

What is the anemia like?
B+/B+ Type 2 or 3
-moderate micro/hypo anemia
What thalassemias have a normal RDW?
Which has an abnormal?
Intermed/minor = normal RDW
Major = increased RDW
what type of gen defects cause minor B thal?

What type of anemia, how severe?
Bo/B (causes major too!?),
B+/B type 1 or 2

mild hypo/micro anemia - usually asymptomatic.
What is the percentage of Hbs in Thal minor?
HbF is <5%
HbA2 is 4-10% (never more)
HbA is majority
As the severity of the B thal decreases what happens to %HbF?
It decreases. Parallel relationship
When does ALPHA thalassemia first become evident?

at birth, or even in utero.

B/c lack of Alpha chains means lack of all Hb. Early in birth there is embryonic Hb so can survive until birth.
What are the characteristic Hb forms that form in Alpha thal?
-Hb Barts -> excess y chains (y4)

-HbH -> excess BETA (b4)
How many sites can there be alpha chain variation/deletion?
4 total, because 2 on each chromosome control a genes, and one from each parent.
what a thalassemia is incompatible with life?
4 gene deletion.
How many alpha thals are there?
4 - correspond to how many genes are deleted or mutated. one, two, 3, 4...
What is hydrops fetalis, what causes it?

what nationalities is it found in?
4-gene deletion alpha thal; no alpha chains, so Hb Bart's is dominant Hb.

-SE asians and occasionally in mediterraneans.
What alpha thal does HbH predominate in?
What beta thal is this like?
What is the anemia?
3-gene deletion.
-Similar to Bthal intermediate
-Anemia is hypo/micro, and cells have HbH inclusions.
What population is Alpha thal 3-gene deletion found in?
Southeast asians
what are 2 types of a thal 2-gene deletion?
What b-thal does it mimic?
What type of anemia/electroph?
-Cis Asian (- -, a a)
-Trans African (- a, - a)
-similar to bthal minor
-hypo/micro anemia is SLIGHT
-electrophoresis is normal
what is another name for one-gene deletion a thal?
SILENT CARRIER -adults are completely normal, babies have a little bit of Hb Bart's.
What is the only hemoglobin present in Delta-Beta thalassemia?
Homozygote has only HbF - gamma chains, -No HbA2, -No HbA.

Hetero has normal A2, increased F, and decr. A1
What occurs in Hb lepore?
Beta and Delta genes fuse so neither chain is produced.

Thalassemia MAJOR
What are the clinical features of a Thalassemia major?
-Lethal in 1st 2 yrs if untreat
-Severe bone deformities b/c of marrow hyperplasia
-Needs blood transfusions, can have iron overload as result.
-Suscept. to infection, need early treatment.
-Might need bone marrow transplant.
What are the clinical features of Thalassemia intermedia?
-Anemia will show symptoms
-Not transfusion dependent
-Chronic state will show elev bilirubin, gallstones
-Iron overload late in life
What are the clinical features of Thalassemia minor?
-MINOR hypo/micro anemia
-Asymptomatic except in stress and pregnancy, acute infection, folic acid deficiency.
What type of CBC and indices are in thalassemia?
-Specific to Major?
-Decreased Hb, Hct, MCH, MCV.
-RDW is normal, MCHC norm to increased.
-Thal major: moderate to increased RDW.
When do you need to differentiate btwn Fe deficiency and Thalassemia?
When the MCV is higher than 70, and the RDW is increased.
What lab indices are characteristic of Thalassemia heterozygous?
-MCH = 22pg
MCV = less than 70fL
Hb = 9-11 g/dl
What does the PBS show in homozygous Beta thal? (that is Thalassemia major)
-Extreme Aniso/Poik
-Ovalocytes, nRBCs, Polychrom.
-Marked hypo/micro
-Heinz Bodyh like inclusions on a supravital stain.
How does a heterozygous beta thal compare to homo on a PBS?
-instead of Extreme, poik/aniso are moderate.
-SOME targets
-some basophilic stippling
-Micro/hypo cells
What is the characteristic findings for HbH - alpha thal?
-Moderate aniso, poik, targets, and baso stipp -> same as heterozygous beta thal.
-Micro/hypo cells
-Increased retic
-HbH inclusions
What type of PBS is seen for
-Alpha thal, 1 gene deletion
-Alpha thal, 2 gene deletion
1 gene = normal CBC and smear
2 gene = MILD hypo/micro
How are HbF levels measured?
Kliehauer-Betke acid elution stain. HbF resists the acid more than other Hbs.
For what 2 purposes would you do iron studies in thalassemias?
1. To differentiate btwn Fe defic. anemia and Beta thal minor
2. To evaluate iron overload in Thal major.

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