Immunology - Immunodeficiencies Flashcards by Sharmili Balarajah

What is the defect in X-linked agammsglobulinaemia?

Defect in BTK —> absence of B cell maturation

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Mode of inheritance for X-linked agammaglobulinaemia

X-linked recessive

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

After 6 months (reduced maternal IgG)

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

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

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What is contraindicated in X linked agammaglobulinaemia?

Live vaccines

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What is the defect in hyper-IgM syndrome?

Defective CD40L on T cells —> class switching defect

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Mode of inheritance for hyperIgM syndrome

X linked recessive

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

Progenitor; opportunistic

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

CMV, Pneumocystis, Cryptosporidium

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Do those with hyperIgM have germinal centres?

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

Decreases

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What is the most common primary immunodeficiency?

Selective IgA deficiency

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

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

Giardiasis

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What is the defect in CVID?

Defect in B cell differentiation

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What is the age of presentation of CVID?

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

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

Bronchiectasis
Sinopulmonary infections

Lymphoma

AI disease

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

Decreases

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What chromosomal abnormality is found in DiGeorge syndrome?

22q11 deletion

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What is the aetiology in DiGeorge syndrome?

Failed development of 3rd & 4th pharyngeal pouches

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What is the presentation of DiGeorge syndrome? (3)

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

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What do investigations show in DiGeorge syndrome?

Hypocalcaemia
Low PTH
Low T cells
Absent thymic shadow on CXR

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Mode of inheritance IL-12 receptor deficiency

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AR inheritance

What happens in IL-12 receptor deficiency?

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Reduced Th1 response

Presentation of IL-12 deficiency

Disseminated mycobacterium & fungal infections | May present after BCG vaccine

Lab findings in IL-12 receptor deficiency

Low IFN-gamma

Mode of inheritance hyperIgE syndrome

AD inheritance

What is the defect in hyperIgE syndrome?

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

Presentation of hyperIgE (Job) syndrome

‘FATED’ - coarse Facies - cold staph Abscesses - retained primary Teeth - raised IgE - Dermatological problems (eczema) Bone #s from minor trauma

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

Th2 > Th1 response

What is the defect in chronic mucocutaneous candidiasis?

T cell dysfunction | Can result from congenital defects in IL-17 or IL-17 receptors

Presentation of chronic mucocutaneous candidiasis

Noninvasive Candida infections skin & mucous membranes

Mode of inheritance SCID

X-linked recessive

Defects in SCID (2)

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

Presentation SCID

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

Clinical findings of SCID on is

Reduced T cell receptor excision circles (TRECs) Absence of - thymic shadow (on CXR) - germinal centres (LN bx) - T cells (flow cytometry)

Defect in ataxia-telangiectasia

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

Mode of inheritance of ataxia telangiectasia

AR inheritance

Presentation of ataxia telangiectasia (3)

Triad - Ataxia (cerebellar defects) - spider Angiomas (telangiectasias) - IgA deficiency (sinopulmonary and GI infections)

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

Lymphoma & leukaemia

What happens to level of AFP in ataxia telangiectasia?

Increased

What is the defect in Wiskott-Aldrich syndrome?

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

Mode of inheritance Wiskott-Aldrich syndrome

X-linked recessive

Presentation of Wiskott-Aldrich syndrome

``` WATER: Wiskott- Aldrich Thrombocytopenia Eczema Recurrent (pyogenic) infections ``` Increased risk AI disease & malignancy

Mode of inheritance leukocyte adhesion deficiency

AR inheritance

Defect in leukocyte adhesion deficiency (type 1)

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

Presentation of leukocyte adhesion deficiency (type 1)

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

What happens to number of neutrophils in blood?

Increases

What is the defect in Chediak-Higashi syndrome?

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

Mode of inheritance Chediak-Higashi syndrome

AR inheritance

Presentation of Chediak-Higashi syndrome

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

Findings in granulocytes and platelets in Chediak-Higashi

Giant granules

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

Mild coagulation defects | Pancytopenia

What is the defect in chronic granulomatous disease?

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

Mode of inheritance chronic granulomatous disease

X-linked

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

Catalase +ve | SPACE - Staphylococci, PsA, Aspergillus fumigatus, Candida, Enterobacteriaceae - Klebsiella, Serratia

Lab investigations for chronic granulomatous disease. (2)

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

Immunology - Immunodeficiencies Flashcards

(57 cards)