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HEM Exam 1 > Hemoglobinopathies > Flashcards

Hemoglobinopathies Flashcards

1
Q

definition of thalassemia

A
  • genetically heterogenous condition resulting from imbalance between amounts of alpha and beta globin chains that are synthesized
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2
Q

thalassemias arise from

A
  • mutations which partially or completely inactivate production of alpha or beta globin chains
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3
Q

inactivation of alpha chain is generally

A
  • full deletion
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4
Q

inactivation of beta chain is generally

A
  • point mutations
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5
Q

ways to classify thalassemias

A
  • severity of clinical manifestations
  • major hemoglobin species formed
  • genotype
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6
Q

symptoms of thalassemia minor

A
  • mild symptoms if any
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7
Q

symptoms of thalassemia major

A
  • severe symptoms

- patients are transfusion dependent

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8
Q

symptoms of thalassemia intermedia

A
  • between major and minor

- patients not transfusion dependent

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9
Q

B^0 thalassemia

A
  • mutations cause absent beta globin synthesis
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10
Q

B+ thalassemia

A
  • mutations cause decreased (but still present) beta globin synthesis
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11
Q

another name for beta thalassemia major

A
  • Cooley’s anemia
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12
Q

genotype of beta thalassemia major

A

B^0/B^0

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13
Q

when does severe anemia develop in beta thalassemia major

A
  • 2-12 months

- infants make gamma, delta, and alpha, not beta yet

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14
Q

beta thalassemia major seen in which population

A
  • mediterraneans
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15
Q

beta thalassemia major diagnosis by

A
  • hemoglobin electrophoresis showing alpha 4 tetramers

- absence of normal hemoglobin A

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16
Q

beta thalassemia major symptoms

A
  • anemia
  • splenomegaly - worsens due to sequestration
  • bony deformities
  • iron overload issues
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17
Q

iron overload issues

A
  • bronze skin
  • liver failure
  • endocrine failure
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18
Q

instability of alpha tetramers leads to

A
  • ineffective erythropoiesis

- destruction of produced RBCs

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19
Q

infective erythropoiesis example

A
  • intramedullary hemolysis
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20
Q

intramedullary hemolysis

A
  • hemolysis of RBC precursors inside marrow
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21
Q

anemia leads to

A
  • increased epo production

- more ineffective erythropoiesis

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22
Q

bone deformities caused by

A
  • marrow expansion
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23
Q

iron overload develops due to

A
  • transfusions

- iron hyper absorption from gut

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24
Q

beta thalassemia minor (trait) genotype

A
  • B+/B^0
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25
Q

beta thalassemia trait symptoms

A
  • generally asymptomatic

- not so many alpha 4 tetramers

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26
Q

beta thalassemia trait MCV

A
  • microcytic

- around 70

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27
Q

beta thalassemia trait anemic

A
  • may or may not be

- mild if present

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28
Q

beta thalassemia trait RBC count

A
  • very elevated
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29
Q

beta thalassemia trait RDW

A
  • normal

- since all cells will be microcytic and hypochromic

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30
Q

beta thalassemia trait diagnosis by

A
  • hemoglobin electrophoresis
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31
Q

beta thalassemia trait - hemoglobin electrophoresis in adults shows

in newborns

A
  • unregulation of delta chains
  • around 4-8% Hgb A2

not seen in newborns since species are predominantly HbF

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32
Q

alpha thalassemia one gene deletion symptoms

A
  • typically silent

- maybe minimal microcytosis

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33
Q

alpha thalassemia one gene deletion anemia

A
  • anemia not present
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34
Q

alpha thalassemia one gene deletion Hb electrophoresis result

A
  • normal
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35
Q

alpha thalassemia two gene deletion symptoms

A
  • mildly anemic
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36
Q

alpha thalassemia two gene deletion MCV

anemic?

A
  • mildly microcytic
  • MCV around 70

mildly anemic (Hg 10-11)

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37
Q

alpha thalassemia two gene deletion Hb electrophoresis in adults

A
  • normal
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38
Q

alpha thalassemia two gene deletion Hb electrophoresis in newborns

A
  • abnormal

- will make hemoglobin Barts (gamma 4)

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39
Q

alpha thalassemia two gene deletion seen in africans

A
  • a-/a-

- trans deletion

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40
Q

alpha thalassemia two gene deletion seen in asians

A
  • aa/–

- cis deletion

41
Q

hemoglobin H disease genotype

A
  • a-/–

- three gene deletion

42
Q

hemoglobin H disease results

A

Hemoglobin H = Beta 4 tetramers

43
Q

hemoglobin H (beta 4 tetramers) form

causes

A
  • Heinz bodies

- causes bite cells and hemolytic anemia

44
Q

hydrops fetalis genotype

A

–/–

45
Q

hydrops fetalis result

A
  • 4 gamma tetramers
  • Hemoglobin barts
  • no alpha chains form
46
Q

hydrops fetalis in utero

A
  • intrauterine death
47
Q

hydrops fetalis treatment

A
  • treated in utero

- exchange transfusions

48
Q

hemoglobin S amino acid switch

A
  • Glu 6 changed to Val 6
49
Q

deoxy HbS compared to HbA

A
  • less soluble

- polymerizes and forms long fibers

50
Q

hemoglobin C amino acid switch

A
  • Glu 6 to Lys 6
51
Q

hemoglobin C result

A
  • leads to increased cellular dehydration
52
Q

hemoglobin C cells found

population targeted

A
  • target cells
  • hemoglobin c crystals

west African descent

53
Q

HbS polymerizes and cell sickle in conditions under

A
  • hypoxia

- acidosis

54
Q

Leads to cellular dehydration

A
  • multiple cycles of sickling and unsickling
55
Q

cells in HbS eventually become

A
  • irreversibly sickled

- obstruct small blood vessels

56
Q

sickled and unsickled red cells suffer

A
  • hemolysis
57
Q

sickled cells and endothelial cells

A
  • abnormal adhesion to endothelial cells
58
Q

sickle cell disease genotype

A
  • homozygous SS
59
Q

S/B^0 thalassemia

A
  • indistinguishable from SS
60
Q

S/B+ thalassemia

A
  • milder disease

- some normal beta chains are produced

61
Q

the presence of HbC and HbS

A
  • leads to more intracellular dehydration

- worsening sickling

62
Q

if Hgb falls below patient’s baseline in sickle cell disease

A
  • look for other causes
  • Parvovirus B19
  • splenic or hepatic sequestration
  • acute chest syndrome
63
Q

leukocytes and platelets in sickle cell disease

A
  • leukocytosis - elevated WBC

- thrombocytosis - elevated platelets

64
Q

spleen in SS adult patients

A
  • functionally asplenic

- spleen has infarcted

65
Q

cells seen in functionally asplenic patients

A
  • Howell jolly bodies
66
Q

sickle cell disease thromboses

A
  • increased risk for venous clots

- risk present in sickle cell trait as well

67
Q

sickle cell crises

A
  • splenic sequestration crisis
  • aplastic crisis
  • painful (vaso-occlusive) crisis
68
Q

splenic sequestration crisis in children

A
  • rapid and extensive trapping of RBCs in spleen
69
Q

splenic sequestration crisis symptoms

A
  • profound anemia
  • massive splenomegaly
  • hypovolemic shock
  • occurs quickly
70
Q

which sickle cell crisis is most common

A
  • painful (vaso-occlusive) crisis
71
Q

painful crisis

how to treat

A
  • periodic episodes of acute vascular occlusion
  • treat pain
  • supplemental O2
  • folate replacement
  • replace fluid
72
Q

painful crisis usually affects

A
  • bones and large joints
73
Q

painful crisis triggers

A
  • exercise
  • dehydration
  • infection
  • cold
  • stress
  • menstruation
  • surgery/trauma
  • pregnancy
74
Q

autospenectomy from sickle cell disease makes patient more susceptible to infections by

A
  • infections by encapsulated organisms
75
Q

sickle cell disease makes patient more susceptible to sepsis by

A
  • encapsulated organisms
76
Q

sickle cell disease infection by ______ if undergoing iron chelation therapy

A
  • yersinia

- vibrio

77
Q

sickle cell disease osteomyelitis and septic arthritis caused by

A
  • salmonella osteomyelitis
78
Q

respiratory complication of sickle cell disease

A
  • acute chest syndrome

- pulmonary hypertension

79
Q

most common cause of death in patients with sickle cell disease

A
  • acute chest syndrome
80
Q

acute chest syndrome definition symptoms

A
  • hypoxemia
  • new infiltrate on CXR
  • new fever, chest pain, dyspnea, or cough
81
Q

infections in acute chest syndrome usually with

A
  • atypical organisms

- chlamydia and mycoplasma

82
Q

acute chest syndrome etiologies

A
  • fat embolism from necrotic bone marrow
  • sequestration of sickled red cells
  • pulmonary infarction
  • hypoventiliation from rib infarct, narcotic administration
  • pulmonary edema from fluid overload
83
Q

treatment of acute chest syndrome

A
  • antibiotics, oxygen

- simple transfusion to lower HbS concentration

84
Q

pulmonary hypertension occurs in what fraction of SCD adults

A
  • 1/3
85
Q

median age of stroke in SCD patients

A
  • 5 years old
86
Q

stroke cause in SCD patients

A
  • disordered blood vessels

- not due to atherosclerosis

87
Q

acute treatment of stroke in SCD patients

A
  • exchange transfusion
88
Q

chronic treatment of stroke in SCD patients

A
  • chronic regular transfusions
89
Q

if transcranial dopplers show narrowing in the circle of Willis then chronic regular transfusions will prevent

A
  • chronic regular transfusions prevent first instance of stroke
90
Q

in an adult, one unit of blood raised Hb by

A

1

91
Q

complications of transfusion in SCD

A
  • iron overload
  • allo-immunization
  • leg ulcers
  • renal
  • AVN
  • priapism
  • proliferative retinopathy
92
Q

organ damage associated with iron overload

A
  • heart failure
  • liver failure
  • endocrine failure
93
Q

treatment for iron overload

A
  • chelation
94
Q

how to avoid allo-immunization in AA

A
  • transfuse blood negative for C, E, Kell blood groups

- reduce frequent transfusion in AA

95
Q

treatment of sickle cell

A
  • hydroxyurea
96
Q

how hydroxyurea works

A
  • increases amount of HbF

- decreases concentration of HbS

97
Q

effects of hydroxyurea

A
  • increases baseline hemoglobin values
  • reduces number of sickle cell crises
  • reduces episodes of acute chest syndrome
  • prevent pulmonary hypertension
  • reduces mortality
98
Q

side effect of hydroxyurea

A
  • bone marrow suppression
99
Q

contraindications for hydroxyurea

A
  • pregnancy

- poor/erratic followup

HEM Exam 1 (22 decks)

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