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40 Cards in this Set
- Front
- Back
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what exactly is thalassemia?
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inherited cause of anemia, by decreased production of a Hb chain. Result of a gene deletion
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Why is such anemia seen in thalassemia?
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B/c the spleen prematurely destroys cells with precipitated chains in excess - Howell jolly bodies.
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What type of anemia is a thalassemia, compared to hbopathy?
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Hypo/micro, instead of normo/normo!
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What are the 2 major results of Beta Thalassemia?
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-Decreased Beta chains
-Compensating increase in HbA2 and HbF b/c don't have Beta. |
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When do you first notice Beta thalassemia? Why?
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After birth, in the 1st year. B/c most Hb at birth is Fetal -> a2y2, so decreased Beta doesn't matter.
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What is the Major diagnosing characteristic of Beta thal?
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Decreased HbA,
Increased HbA2 and HbF |
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What does Bo mean?
What does B+ mean? |
Bo = complete absence of Beta chains from this gene.
B+ = decreased production. |
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What culture is Bo most seen in?
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Mediterraneans
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How much Beta chain is produced from a B+ gene?
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there are types 1,2,3.. in general we say about 50%
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What type of gene combo causes Beta thal Major?
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Bo/Bo
B+/B+ (if type 1) Bo/Bnormal |
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what are the major symptoms of a Beta thal major?
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-Severe micro/hypo anemia
-HbF like 90%, increased HbA2 and absent/none of HbA1 -Skeletal changes |
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What type of gene defect is intermediate B thal?
What is the anemia like? |
B+/B+ Type 2 or 3
-moderate micro/hypo anemia |
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What thalassemias have a normal RDW?
Which has an abnormal? |
Intermed/minor = normal RDW
Major = increased RDW |
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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. |
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What is the percentage of Hbs in Thal minor?
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HbF is <5%
HbA2 is 4-10% (never more) HbA is majority |
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As the severity of the B thal decreases what happens to %HbF?
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It decreases. Parallel relationship
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When does ALPHA thalassemia first become evident?
Why? |
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. |
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What are the characteristic Hb forms that form in Alpha thal?
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-Hb Barts -> excess y chains (y4)
-HbH -> excess BETA (b4) |
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How many sites can there be alpha chain variation/deletion?
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4 total, because 2 on each chromosome control a genes, and one from each parent.
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what a thalassemia is incompatible with life?
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4 gene deletion.
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How many alpha thals are there?
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4 - correspond to how many genes are deleted or mutated. one, two, 3, 4...
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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. |
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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. |
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What population is Alpha thal 3-gene deletion found in?
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Southeast asians
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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 |
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what is another name for one-gene deletion a thal?
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SILENT CARRIER -adults are completely normal, babies have a little bit of Hb Bart's.
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What is the only hemoglobin present in Delta-Beta thalassemia?
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Homozygote has only HbF - gamma chains, -No HbA2, -No HbA.
Hetero has normal A2, increased F, and decr. A1 |
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What occurs in Hb lepore?
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Beta and Delta genes fuse so neither chain is produced.
Thalassemia MAJOR |
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What are the clinical features of a Thalassemia major?
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-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. |
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What are the clinical features of Thalassemia intermedia?
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-Anemia will show symptoms
-Not transfusion dependent -Chronic state will show elev bilirubin, gallstones -Iron overload late in life |
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What are the clinical features of Thalassemia minor?
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-MINOR hypo/micro anemia
-Asymptomatic except in stress and pregnancy, acute infection, folic acid deficiency. |
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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. |
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When do you need to differentiate btwn Fe deficiency and Thalassemia?
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When the MCV is higher than 70, and the RDW is increased.
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What lab indices are characteristic of Thalassemia heterozygous?
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-MCH = 22pg
MCV = less than 70fL Hb = 9-11 g/dl |
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What does the PBS show in homozygous Beta thal? (that is Thalassemia major)
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-Extreme Aniso/Poik
-TARGETS -Ovalocytes, nRBCs, Polychrom. -Marked hypo/micro -Heinz Bodyh like inclusions on a supravital stain. |
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How does a heterozygous beta thal compare to homo on a PBS?
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-instead of Extreme, poik/aniso are moderate.
-SOME targets -some basophilic stippling -Micro/hypo cells |
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What is the characteristic findings for HbH - alpha thal?
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-Moderate aniso, poik, targets, and baso stipp -> same as heterozygous beta thal.
-Micro/hypo cells -Increased retic -HbH inclusions |
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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 |
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How are HbF levels measured?
Why? |
Kliehauer-Betke acid elution stain. HbF resists the acid more than other Hbs.
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For what 2 purposes would you do iron studies in thalassemias?
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1. To differentiate btwn Fe defic. anemia and Beta thal minor
2. To evaluate iron overload in Thal major. |
