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Heme boards > Thalassemias > Flashcards

Thalassemias Flashcards

1
Q

Sickle cell-beta0 thalassemia vs. sickle cell-beta+ thalassemia

A
  • beta0 = complete absence of beta globin (so no Hb A production (which is a tetramer of A2B2))
  • beta+ = reduced amounts of beta globin
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2
Q

Hgb electrophoresis pattern of hbg S-beta0 thalassemia

A

*similar to Hb SS so it is hard to differentiate Hb SS from Hb S-beta thal
- nearly all Hb S
- no Hb A present

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3
Q

Clinical feature of hbg S-beta0 thalassemia

A
  • as severe phenotype as homozygous SCD (since no Hb A production)
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4
Q

Clinical feature of hbg S-beta+ thalassemia

A
  • more mild since they still have some beta globin production
  • milder course than HB s -beta0 but may still have life-threatening episodes of acute chest, pain crises
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5
Q

Lab features of hbg S-beta+ thalassemia

A
  • anemia, microcytosis
  • Hb A fraction (5-30%)
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6
Q

Hbg E clinical features

A

asymptomatic with minal anemia and microcytosis

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7
Q

Most common form of hemoglobin in humans and structure

A
  • hemoglobin A, which consists of 2 alpha subunits and 2 beta subunits
  • hemoglobin A2 accounts for only 1-3%
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8
Q

alpha thal pathophysiology

A

defective alpha globin gene production - typically deletional

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9
Q

constant spring anemia - 1) ethnicity more prevalent in 2) clinical features

A

nondeletional subtype of alpha thal (deletional is far more common)
- southeast Asian
3) significant anemia, frequently requiring transfusions

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10
Q

Hgb A makeup (dominant hemoglobin in adults)

A

2 alpha units, 2 beta units

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11
Q

Alpha thal sequelae

A

heart failure, arrhythmias
iron overload
VTE
leg ulcers

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12
Q

normal hgb electrophoresis

A

hgb a (95%)
hgb a2(2-3%)
hgb F (1-2%)

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13
Q

alpha thal silent carrier (alpha thal minima) 1) presentation 2) hgb electrophoresis pattern

A

1) microcytosis, otherwise normal
2) normal (only one alpha gene missing)

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14
Q

alpha thal trait 1) presentation 2) hgb electrophoresis

A

1) mild microcytosis (deletion of 2 alpha genes).
*Looks like iron deficiency given low MCV
2) normal electrophoresis (need genetic testing)

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15
Q

hemoglobin H disease 1) physiology 1.5) clinical presentation 2) IHC stain that is positive 3) hgb electrophoresis

A

1) 3 alpha allele deletions, thus beta chain tetramers form (HbH)
1) variable, mild to moderate anemia, some transfusion dependent, others are not.
*They have intermittent anemia from infection, pregnancy, exposure to oxidant drugs.
2) Brilliant cresyl blue stain (stains inclusions)
*See photo online
3) hgb H peak (ranging 5-40%)

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16
Q

hemoglobin barts is

A

alpha thal major (hydrops fetalis)
*deletion of all 4 alpha genes so no synthesis of alpha chains and most hb is Hb barts (composed of gamma chains)

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17
Q

alpha thal major presentation

A
  • typically death in utero, some survive with
  • neurodevelopmental delays
  • congenital anomalies
  • growth delays
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18
Q

alpha thal major treatment

A
  • iron chelation at age 1
  • transfusions in utero and lifelong
  • consideration of transplant
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19
Q

ATRX alpha thalassemia

A

X linked alpha thal associated with intellectual disability in young boys

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20
Q

Structure of hgb F

A

2 alpha chains, 2 gamma chains

21
Q

Structure of hgb A2

A

2 alpha chains, 2 delta chains

22
Q

Structure of hgb A1

A

2 alpha chains, 2 beta chains

23
Q

beta thalassemia minor - 1) labs

A

1) microcytosis with mild or no anemia

24
Q

beta thalassemia minor hgb electrophoresis

A
  • mild increase in hgb A2 (, increase in delta chains in response to beta loss)
    **SO remember HbA2>3.5%
25
Q

beta thalassemia minor managment

A

observation

26
Q

beta thalassemia major (b0b0) clinical features

A
  • severe anemia seen in infancy
  • iron overload from ineffective erythropoesis
  • splenomegaly with functional asplenia
  • osteoporosis
  • hemolysis
27
Q

beta thalassemia intermedia physiology

A

Either B+b0 or B+B+ (decrease in beta chain)

28
Q

beta thalassemia major hgb electrophoresis

A
  • no hgb A1 (can’t make beta chains)
    *see alpha tetramers instead
29
Q

transfusion dependent beta thalassemia management

A

luspatercept

30
Q

hgb E 1) physiology 2) area with highest prevalence 3) homozygote presentation

A

1) point mutation leading to decrease in beta chain
2) Indian
3) minimal anemia with target cells

31
Q

hgb lepore

A
  • unequal recombination of beta and delta genes, resulting in stable globin
    *has mobility of hgb S on electrophoresis so may look like sickle cell anemia on electrophoresis and looks like hgb A on acid electrophoresis
32
Q

beta thalassemia minor physiology

A

B(normal)B+ or B(normal)B0

33
Q

Alpha globin loci is located on what chromosome

A

16

34
Q

Beta globin Loci is located on which chromosome

A

11

35
Q

Hgb barts is composed of

A

gamma chains (alpha loss leads to increased gamma)

36
Q

Other condition in which alpha thalassemia can develop

A

MDS

37
Q

Transfusion target in transfusion dependent thalassemia

A

Hgb 9.5 (significantly reduced complications with higher transfusion threshold)

38
Q

Most common endocrinopathy in thalassemia pts

A

Hypogonadotropic hypogonadism (Iron deposits in pituitary gland from iron overload)

39
Q

Target ferritin in transfusion dependent thalassemia pts

A

Less than 1000

40
Q

Deferoxamine SE’s

A
  • hearing loss
  • yersinia infection
  • vision changes
  • bone changes
41
Q

Deferiprone SE’s

A
  • neutropenia
  • arthralgias
42
Q

deferasirox SE’s

A
  • AKI
  • elevated liver enzymes
  • GI bleeding
43
Q

Luspatercept SE’s

A
  • VTE
  • HTN
  • concern for worsening extramedullary hematopoietic masses (eg paraspinal masses)
44
Q

Approved gene therapy for thalassemia

A

1) Betibeglogene autotemcel (beti-cel)
2) Exagamglogene autotemcel (exa-cel) - uses CRISPR

45
Q

Contraindication to luspatercept in thalassemia

A

Paraspinal masses

46
Q

Homozygous hemoglobin C clinical features

A
  • mild hemolytic anemia
  • gallstones
  • splenomegaly
47
Q

Hemoglobin M disorder clinical features

A
  • asymptomatic cyanosis
  • slate gray/brownish skin
    *(hereditary methhemoglobinemia)
48
Q

Hemoglobin M treatment

A

No treatment required

49
Q

Abnormal MRI threshold for iron overload

A

T2 MRI <20 milliseconds

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