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MDTI > Hemoglobinopathies > Flashcards

Hemoglobinopathies Flashcards

1
Q

hemoglobinopathy definition

A

disorder involving hemoglobin

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2
Q

disorder involving heme

A

porphyria

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3
Q

globins expressed embryonically

A

epsilon

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4
Q

globins expressed fetally

A

gamma, alpha (HbF)

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5
Q

globins expressed in adults

A

alpha, beta (HbA) & alpha, gamma (HbA2)

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6
Q

what types of deletions tend to affect the alpha globin?

A

deletional mutations leading to zero condition (no production)

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7
Q

what types of deletions tend to affect the beta globin?

A

nondeletional mutations which tend to lead to plus mutations (decreased production)

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8
Q

types of nondeletional mutations

A

transcription, mRNA processing, transport, translation, mRNA stability, protein function mutations

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9
Q

composition of typical adult hemoglobin

A

two alpha, two beta globins and heme

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10
Q

structural hemoglobinopathies

A

qualitative defects in hemoglobin function

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11
Q

examples of structural hemoglobinopathies

A

sickle hemoglobins, low/high O2 affinity, unstable hemoglobins, methermoglobins

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12
Q

thalassemia definition

A

quantitative defects in hemoglobin production (Hb made is normal, just not enough is made)

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13
Q

types of thalassemias

A

alpha, beta, hereditary persistence of fetal, fusion hemoglobins

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14
Q

most important thing to know about severity of thalassemia****

A

the degree of alpha/beta chain imbalance predicts the severity of the phenotype***

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15
Q

characteristics of thalasemmia anemia

A

microcytic, hypochromic

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16
Q

alpha thalassemia

A

deficiency in HbA (alpha/beta) with excess HbH (beta/beta)

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17
Q

HbH

A

beta homotetramer hemoglobin corresponding with alpha thalassemia. soluble and nontoxic

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18
Q

alpha thalassemia trait

A

-a/-a or –/aa. quite mild (slightly low levels of Hb, and slightly small MCV)

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19
Q

HbH disease

A

–/-a. high levels of HbH present. still quite mild symptoms

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20
Q

hydrops fetalis

A

–/–. complete alpha thalassemia. fatal before birth

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21
Q

most common alpha thalassemia in blacks

A

-a/-a. common but not an issue for offspring

22
Q

most common alpha thalassemia in asians

A

aa/– common, which can lead to hydrous fetalis in offspring

23
Q

beta thalassemia

A

deficiency in Hb (alpha/beta) and excess alpha homotetramers, which precipitate and are toxic!

24
Q

beta thalassemia minor (trait)

A

B/B* (one of two genes is defective). decreased Hb & MCV. Increase HbA2 as compensation

25
Q

beta thalassemia intermedia

A

B+/B* (two defective genes with one mutation being milder) or B+/B+ (two mild mutations). vast phenotypes, anemia, low MCV

26
Q

beta thalassemia major

A

B/B (two defective genes). very anemic, very low MCV, 10% HbA2, 90% HbF as compensation.

27
Q

characteristic most indicative of beta thalassemia?

A

increased HbA2 levels!

28
Q

clinical presentation of severe beta thalassemia

A

family history, ethnic background, poor growth/development, jaundice, frontal bossing, splenomegaly, hypochromic/microcytic anemia with targeting, normal iron levels, INCREASED HBA2

29
Q

consequences of alpha homotetramer precipitation

A

erythroid progenitor membrane damage=ineffective erythropoiesis & RBC membrane damage=accelerated removal=hemolytic anemia
—>both lead to profound anemia

30
Q

consequence of ineffective erthyroid mass due to profound anemia in beta thalassemia?

A

compensatory erythropoiesis (marrow from atypical locations, frontal bossing) & extra medullary erythropoiesis (splenomegaly)

31
Q

most common causes of microcytic anemia

A

iron deficiency & thalassemia

32
Q

distinguish iron deficiency vs beta thalassemia

A

TEST IRON LEVELS

33
Q

DIAGNOSE: Hb=9, MCV=74, Ferritin=2

A

Iron deficient anemia

34
Q

DIAGNOSE: Hb=11, MCV=65, Ferritin=Nl

A

thalassemia

35
Q

DIAGNOSE: A=94%, A2=5%, F=0%

A

increased A2=beta thalassemia minor (major would have higher A2, like 10% and increased F)

36
Q

DIAGNOSE: Hb=3.5, MCV=57, Ferritin=1822

A

thalassemia

37
Q

DIAGNOSE: A=0, A2=10%, F=90%

A

beta thalassemia major

38
Q

treatment for thalassemia

A

PRBC transfusion or chelating agents (remove iron), bone marrow transplant

39
Q

genetic basis of sickle cell disease

A

single missense mutation that results in Glu–>Val substitution in beta globin

40
Q

cause of sickle shape?

A

when deoxygenated, Hb assembles into long polymer fibers that destroy RBC membrane structure.

41
Q

theories on pathophysiology of sickle disease

A

log jam model, RBC dehydration, cellular adhesion, reduced NO bioavailability

42
Q

treatment for chronic sickle cell disease

A

hydroxyurea=inducer of fetal gamma glob in (no hydrophobic site for polymerization). bone marrow transplant

43
Q

blood characteristics of sickle cell disease

A

moderate anemia, normocyti/normochromic RBCs, drepanocytes (sickle)

44
Q

AA Hb electrophoresis

A

A=97, A2=<3, F=0, S=0

45
Q

AS Hb electrophoresis

A

A=60, A2<3, F=0, S=40 (40/60 RULE)

46
Q

SS Hb electrophoresis

A

A=0, A2<10, S=90

47
Q

DIAGNOSE: A=40, A2=5, F=0, S=60

A

co inherited beta thalassemia with sickle cell (B+ reducing levels of A, Bs increasing levels of S)

48
Q

DIAGNOSE: A=80, A2=1.5, F=0, S=20

A

co inherited alpha thalassemia with sickle cell

49
Q

DIAGNOSE: Hb=14, MCV=85, A=59, A2=2, F=0, S=39

A

sickle cell trait

50
Q

DIAGNOSE: Hb=8, MCV=88, A=0, A2=2.5, F=2, S=96

A

sickle cell disease

51
Q

DIAGNOSE: Hb=11, MCV=72, ferritin=477, A=10, A2=7, F=7, S=76

A

coinherited beta thalassemia and sickle cell in beta globin (Bs/B+)

MDTI (42 decks)

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