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USMLE > Immunology - Immunodeficiencies > Flashcards

Immunology - Immunodeficiencies Flashcards

1
Q

What is the defect in X-linked agammsglobulinaemia?

A

Defect in BTK —> absence of B cell maturation

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2
Q

Mode of inheritance for X-linked agammaglobulinaemia

A

X-linked recessive

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3
Q

When do you begin to notice that a child has X-linked agammaglobulinaemia and why?

A

After 6 months (reduced maternal IgG)

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4
Q

What type of infections are individuals with X linked agammabglobulinaemia susceptible to?

A

Recurrent bacterial (extracellular), enteroviral (due to absence of neutralising antibodies)

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5
Q

What is contraindicated in X linked agammaglobulinaemia?

A

Live vaccines

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6
Q

What is the defect in hyper-IgM syndrome?

A

Defective CD40L on T cells —> class switching defect

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7
Q

Mode of inheritance for hyperIgM syndrome

A

X linked recessive

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8
Q

What type of infections are individuals with hyperIgM syndrome susceptible to?

A

Progenitor; opportunistic

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9
Q

Name 3 opportunistic infections that may be seen in hyperIgM syndrome.

A

CMV, Pneumocystis, Cryptosporidium

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10
Q

Do those with hyperIgM have germinal centres?

A

No

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11
Q

What happens to the levels of IgA, IgG & IgE in hyperIgM syndrome?

A

Decreases

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12
Q

What is the most common primary immunodeficiency?

A

Selective IgA deficiency

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13
Q

What are the clinical features of selective IgA immunodeficiency? 5As

A 
Majority Asymptomatic
Can see
- Airway (sinus and lung) and GI sx
- AI disease
- Atopy
- Anaphylaxis to IgA containing products (e.g. blood transfusion)
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14
Q

To which infection in particular are individuals with selective IgA immunodeficiency susceptible to?

A

Giardiasis

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15
Q

What is the defect in CVID?

A

Defect in B cell differentiation

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16
Q

What is the age of presentation of CVID?

A

After 2y.o, can be delayed to 30-40s

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17
Q

What are individuals with CVID susceptible to? (2 infections, 1 malignancy, 1 general)

A

Bronchiectasis
Sinopulmonary infections

Lymphoma

AI disease

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18
Q

What happens to levels of plasma cells and Ig in patients with CVID?

A

Decreases

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19
Q

What chromosomal abnormality is found in DiGeorge syndrome?

A

22q11 deletion

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20
Q

What is the aetiology in DiGeorge syndrome?

A

Failed development of 3rd & 4th pharyngeal pouches

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21
Q

What is the presentation of DiGeorge syndrome? (3)

A

Tetany (hypoCa)
Recurrent fungal/viral infections
Conotruncal abnormalities e.g. Tetralolgy of Fallot, truncus arteriosus

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22
Q

What do investigations show in DiGeorge syndrome?

A

Hypocalcaemia
Low PTH
Low T cells
Absent thymic shadow on CXR

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23
Q

Mode of inheritance IL-12 receptor deficiency

A

AR inheritance

24
Q

What happens in IL-12 receptor deficiency?

A

Reduced Th1 response

25
Q

Presentation of IL-12 deficiency

A

Disseminated mycobacterium & fungal infections

May present after BCG vaccine

26
Q

Lab findings in IL-12 receptor deficiency

A

Low IFN-gamma

27
Q

Mode of inheritance hyperIgE syndrome

A

AD inheritance

28
Q

What is the defect in hyperIgE syndrome?

A

STAT3 mutation —> deficiency Th17 cells —> impaired recruitment of neutrophils to site of infection
Th1 cannot produce IFN-gamma

29
Q

Presentation of hyperIgE (Job) syndrome

A

‘FATED’

  • coarse Facies
  • cold staph Abscesses
  • retained primary Teeth
  • raised IgE
  • Dermatological problems (eczema)

Bone #s from minor trauma

30
Q

Why do you find elevated IgE & eosinophils in hyperIgE syndrome?

A

Th2 > Th1 response

31
Q

What is the defect in chronic mucocutaneous candidiasis?

A

T cell dysfunction

Can result from congenital defects in IL-17 or IL-17 receptors

32
Q

Presentation of chronic mucocutaneous candidiasis

A

Noninvasive Candida infections skin & mucous membranes

33
Q

Mode of inheritance SCID

A

X-linked recessive

34
Q

Defects in SCID (2)

A
  1. Defective IL-2R gamma chain —> reduced T cell activation —> reduced B cell response
  2. Adenosine deaminase deficiency
    Lack of degradation of purines —> toxic for B & T cells
35
Q

Presentation SCID

A

Failure to thrive
Chronic diarrhoea
Thrush
Recurrent infections (viral, bacterial, fungal, protozoal)

36
Q

Clinical findings of SCID on is

A

Reduced T cell receptor excision circles (TRECs)

Absence of

  • thymic shadow (on CXR)
  • germinal centres (LN bx)
  • T cells (flow cytometry)
37
Q

Defect in ataxia-telangiectasia

A

Defect ATM gene —> failed detection DNA damage —> accumulation of mutations

38
Q

Mode of inheritance of ataxia telangiectasia

A

AR inheritance

39
Q

Presentation of ataxia telangiectasia (3)

A

Triad

  • Ataxia (cerebellar defects)
  • spider Angiomas (telangiectasias)
  • IgA deficiency (sinopulmonary and GI infections)
40
Q

Increased risk of what in ataxia telangiectasia (other than infection)?

A

Lymphoma & leukaemia

41
Q

What happens to level of AFP in ataxia telangiectasia?

A

Increased

42
Q

What is the defect in Wiskott-Aldrich syndrome?

A

Mutation in WASp gene —> leukocytes & platelets unable to recognise actin cytoskeleton —> defective antigen presentation

43
Q

Mode of inheritance Wiskott-Aldrich syndrome

A

X-linked recessive

44
Q

Presentation of Wiskott-Aldrich syndrome

A 
WATER:
Wiskott-
Aldrich
Thrombocytopenia
Eczema
Recurrent (pyogenic) infections

Increased risk AI disease & malignancy

45
Q

Mode of inheritance leukocyte adhesion deficiency

A

AR inheritance

46
Q

Defect in leukocyte adhesion deficiency (type 1)

A

Defect in LFA-1 integrity (CD18) on phagocytes —> impaired migration and chemotaxis

47
Q

Presentation of leukocyte adhesion deficiency (type 1)

A
  • recurrent skin and mucosal bacterial infections
  • absent pus
  • impaired wound healing
  • delayed separation of umbilical cord (>30 days)
48
Q

What happens to number of neutrophils in blood?

A

Increases

49
Q

What is the defect in Chediak-Higashi syndrome?

A

Defect in lysosomal trafficking regulator gene (LYST) —> microtubule dysfunction in phagosome-lysosomes fusion

50
Q

Mode of inheritance Chediak-Higashi syndrome

A

AR inheritance

51
Q

Presentation of Chediak-Higashi syndrome

A

PLAIN

  • Progressive neurodegenerative
  • Lymphohistiocytosis
  • Albinism (partial)
  • Infection - recurrent pyogenic, by staph & strep
  • Neuropathy (peripheral)
52
Q

Findings in granulocytes and platelets in Chediak-Higashi

A

Giant granules

53
Q

What happens to coagulation and FBC in Chediak-Higashi syndrome?

A

Mild coagulation defects

Pancytopenia

54
Q

What is the defect in chronic granulomatous disease?

A

Defect of NADPH oxidase —> reduced reactive oxygen species e.g. superoxide & reduced respiratory burst in neutrophils

55
Q

Mode of inheritance chronic granulomatous disease

A

X-linked

56
Q

Increased susceptibility to what type of organisms in chronic granulomatous disease?

A

Catalase +ve

SPACE - Staphylococci, PsA, Aspergillus fumigatus, Candida, Enterobacteriaceae - Klebsiella, Serratia

57
Q

Lab investigations for chronic granulomatous disease. (2)

A
  1. Dihdyrohodamine (flow cytometry) - reduced green fluorescence
  2. Nitroblue tetrazolium dye reduction test - fails to turn blue

USMLE (3 decks)

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