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
- 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.
- 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.
-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 basophilic stippling
- What is the characteristic findings for HbH - alpha thal?
- -Moderate aniso, poik, targets, and baso stipp -> same as heterozygous beta thal.
- 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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