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Thalassemia Flashcards

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1
Q

1 Hemoglobin consists of

A

4 Fe2+
4 Porphyrin
4 globin chains

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2
Q

globin chain production

A

Required 4 chains of AA
- 2 homologous chains

Alpha = chromosome 16
- alpha (Hgb A1,A2, F, Gower2)
- (hgb Gower 1, portland)

Beta = chromosome 11
- beta (hgb A1)
- delta = hgb A2
- gamma (hgb F, porland
- epsilon (hgb Gower 1 and 2)
-

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3
Q

Hemoglobin F

A

a2y2

60-90% in fetus

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4
Q

Hemoglobin A1

A

a2b2
95-97%
Adult

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5
Q

Hemoglobin A2

A

a2d2

2-3%

Adult

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6
Q

hemoglobin electrophoresis

A

problem: some hgb chains will migrate to the same site.

Combat this by running different types of agar held at different pHs

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7
Q

Cellulose acetate

A

pH: 8.6

Loaded at cathode

Alkaline pH gives hemoglobin a negative charge which travels from (-) cathode to (+) anode

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8
Q

Citrate agar

A

pH: 6.0

Load in center

Hgb chains will travel in either direction depending on its type

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9
Q

Isoelectric focusing

A
  • uses a pH gradient across polychrylamide gel
    1. seperated based on isoelectric point
    2. expensive and slow
    3. creates distinguishable bands
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10
Q

high performance liquid chromatogrpahy

A

pushes sample in solvent (mobile phase) at high pressure through a column of stationary phase material that allows us to seperate and identify compounds

  • expansive and small sample size
  • fully automated and quantitaitve
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11
Q

Kleihauer Betke-Stain / KB stain

A

fetal hgb can be quantified by an acid-elution stain.

acidic pH (3.3) is applied to an air-dried, alcohol fixed blood smear
- hgb A is eluted off
- hgb F is resistant

smear is further treated and stained with eosin or erythrosine
- normal adult red cells - ghost cells (mom)
- hgb F cells - stained baby

Fetal hgb cells can be quantitated to determine fetal trauma in pregant mom or hereditary persistance of hgb f

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12
Q

gower 1
gower 2
portland

A

embryo (z2e2)
embryo (a2e2)
embryo (z2 y2)

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13
Q

hemolytic anemia

A

resulting from the shortened survival of RBCs

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14
Q

RBC destruction lab findings

A

Decreased
- RBC count, hgb, hct
- haptoglobin
- hemopexin

increased
- total bilirubin
- methemal bumin
- hemoglobinemia
- hemoglobinuria
- LDH

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15
Q

RBC count

A

Bone marrow erythroid hyperplasia
(m:e shifting towards E)

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16
Q

osmotic fragility

A

determines RBC hemolysis resitance by placing blood in different concentrations of hypotonic saline

in hypotonic saline… RBC will take in water and swell, until
- reach equilibrium
- cell leaks/ruptures (lyses)

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17
Q

Thalassemia

A
  • Hemolytic anemia
  • hemoglobinopathy
  • microcytic, hypochromic anemia
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18
Q

thalassemia definition

A

group of disorders that result in decreased production of globin chains in hgb resulting in microcytic, hypochromic anemia

defect in alpha or beta chain

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19
Q

thalassa is greek for

A

“sea” or “sea in the blood”

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20
Q

1st discovered by Thomas cooley and Pearl Lee

A
  • first named “cooleys anemia” found in a population of mediterrabeab children

now termed Beta Thalassemia Major

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21
Q

haplotype

A

group of genes inherited together from a single parent

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22
Q

Chain 0

A

gene results in complete absence of globin chain.

ex: a0 or b0

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23
Q

Chain +

A

gene results in reduced production of globin chain

a+ or B+

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24
Q

type of thalassemia is going to named after the chain most affected

A

alpha thalassemia involved missing/mutated alpha genes

same with beta ^

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25
Thalassemia pathophysiology
1. abnormal gene causes failure to produce functional mRNA for specific globin chain 2. any specific globin chain produced are structurally normal, but decreased (or absent) 3. decerase amount of normal hgb(A1) 4. rate of synthesis between a/b are not equal 5. imbalance of 2 types of homologous chains
26
Alpha (a) thalassemia
excess beta and gamma globin chains build up - Hemoglobin Bart's = 4 gamma chains - Hemolgobin H = 4 beta chains tetramers are useless and precipitate in older cells shorten life span by hemolysis
27
hemoglobin bart's
4 gamma chains
28
hemoglobin H
4 beta chains
29
Beta B thalassemia
excess alpha build up forms pairs of a2 pairs precipitate in RBC precursors causes apoptosies in RBC precursors in BM results in ineffective erythropoiesis
30
Beta thalassemia info
- high frequency in mediterranean area - doesn't present until switch is complete from gamma chain syntehsis -> beta chain syntehsis 1. usually after birth 2. clinically seen during 1st year of life body compensates by increase gamma and delta chains to form hgb F and hgb 2
31
B thalassemia - B+
gene produces a reduced amount of beta chains
32
Type 1 B+
10% of normal beta production - least amount of globin chains of the three types
33
Type 2 B+
50% of normal beta production
34
type 3 B+
have a greater amount of beta production and very mild symptoms
35
Normal conditions (B thalassemia)
Genetic haplotype: BB No anemia
36
B Thalassemia Minor
haplotype: BB0, BB+ Also called Beta thalassemia trait
37
B thalassemia intermedia
B+B+ Less severe B+ types
38
B thalassemia Major
B0 B0 B+ B+ B0 B+ Most severe
39
B Thalassemia Minor
BB0 or BB+ - mild increase in Hgb F and Hgb A2 - mild microcytic, hypochromic anemia; although RBC count may be normal/increased Usually asymptomatic, but may see symtpoms if under stress (ex: pregnancy)
40
B thalassemia intermedia
B+ B+, with less severe types - not transfusion dependen t - bridge between minor and major in terms of severity - varible anemia symptoms 1. jaundice 2. splenomegaly 3. long surviving thalassemia symptoms - treatment: supportive therapy with occasional transfusion
41
B thalassemia major
B0 B0, B+B+, B+B0 (homo and heterozygous compounds) Usually begins presentation during first year of life - gamma chain - beta switching symptoms: failure to thrive, pallor, anemia, enlarged spleen jaundice and irritability
42
B thalassemia major pathophysiology
Bone changes (skull, long bones, hand) Liver and spleen enlarge - hepatosplenomegaly
43
B thalassemia major - bone changes
Hand Bone Mongoloid faces - overgrown "moon face" with prominent cheekbones, wide-spaced eyes, sunken nose, flot bones, face rounded. Skull - radiating striations giving typical "hair on end" appearance
44
B thalassemia major - untreated
Children will have numerous complications - *massive hepatosplenomegaly - due to extramedullary erytropiesis * - recurren tinfection - spontanous fractures - leg ulcers - dental problems Usually dies in early childhood or short after birth
45
B thalassemia major - treatment
Lifelong recurrent blood transfusion splenectomy (after 5 yrs old) Future options: BM/ stem cell transplant
46
B thalassemia major - treatment options
Mutliple transfusions + increased iron absorption (ineffective erythropoiesis) = iron overload Transfusion treatment plans should include iron chelation therapy
47
B thalassemia major Lab findings CBC Hemoglobin electrophoresis
CBC - low hgb (2-3 g/dl) - low MCV, MCH, MCHC - Increased RDW Electrophoresis - mostly Hgb F and Hgb A2
48
B thalassemia major - peripheral smear
Microcytic (4+), hypochromic (4+) Anisocytosis and Poikilocytosis Target cells Schistocytes / fragments Basophilic Stippling Accelerated (ineffecive) erythropoiesis - polychromasia - lots of nRBCs - Howell jolly bodies
49
Alpha thalassemia info
- asian populations - manifest in utero or immediately at birth - during fetal life 1. gamma chain build up -After birth 1. beta chain buildup Tetramers of excess chains form: - Hgb Barts = 4gamma chains - Hgb H = 4 beta chains
50
Alpha thalassemia haplotypes
2 alpha (a) genes (a1a2) are present on chromosome 16
51
a0 thalassemia = a thalassemia 1(--)
complete absence of any alpha chains borth alpha genes on chromosome 16 are nonfunctioning
52
a+ thalassemia = alpha thalassemia 2 (-a)
- reduction in output of alpha chains - one gene is functonal and other is nonfunctional
53
normal conditions
aa (aa/aa)
54
silent carrier of alpha thalassemia
aa+ (aa/a-)
55
alpha thalassemia minor
aa0 (aa/--) a+a+ (-a/-a)
56
Hemolgobin H disease
a0a+ (--/-a)
57
Hemoglobin Bart's hydrops fetalis syndrome
a0a0 (--/--)
58
silent carrier of alpha thalassemia
aa+ (aa/a-) small amount of hgb bart's at birth, but disappears during development - eventually leads to normal hgb electrophoresis asymptomatic most of you will see borderline low MCV (78-80 fL)
59
A thalassemia minor
aa0 (aa/--) or a+a+ (-a/-a) - hgb Bart present at birth 5-15% but disappears during development and foes not go on to produce hgb H 1. eventually had normal hgb electrophoresis Mild microcytic, hypochromic anemia
60
Hemoglobin H disease
a0 a+ (--/-a) - variable degree of microcytic, hypochromic anemia and splenomegaly or bone related changes. **5-40% Hgb H (4 beta chains)** remaining is Hgb A1 and A2 Small amounts of Hgb Barts (4 gamma chains) RBC gives "golf ball apperance" with supervital stain
61
Hemoglobin Bart's Hydrops Fetalis Syndrome
a0a0 (--/--) lethal disease - usually stillbirth or spontaneous abortion. no alpha chains produces only Hgb present after embryonic phase is : **Hgb Barts - 4 gamma chains** Length of gestation is dependent on Hgb Portland and Hgb Gower I production since Hgb Bart cannot deliver oxygen
62
Thalassemia general lab findings
CBC - Low Hgb - Low MCV - Low MCH - Low MCHC Iron Studies - N/ High serum iron - high serum ferritin - normal TIBC - normal to high tranaferrin Sat% Peripheral Smear: - microcytic, hypochromia - Reticulocytosis - Poikilocytosis - elliptocytes, target cells, fragments. Osmotic fragility - decreased. due to higher surface to volume ratio

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