Immunodeficiency

Question 1

Hallmark features of immunodeficiency (SPUR):

Answer 1

Serious infections
Persistent infections
Unusual infections
Recurrent infections

Question 2

How is X-linked agammaglobulinemia (XLA) caused, and how does it affects the immune system:

Answer 2

Mutation in BTK gene (X-linked recessive)

Absence or reduction of B cells and all Ig’s by blocking their differentiation and development.

Question 3

How is hyper-IgM caused, and how does this affect the immune system?

Answer 3

Caused by variety of mutations:
- Mutations in CD40L gene
- X linked recessive inheritance
- Defective TFH function

How it affects immune system:
- Reduces memory B cells
- Elevated IgM
- Decreased IgG
- Defective interactions between B and TFH
cells

Question 4

How is X-linked SCID (Severe Combined Immunodeficiency) caused and how does this affect the immune system?

Answer 4

Mutation in the gamma subunit of IL2RG gene

How this effects immune system:
- Cytokines can’t bind to receptors encoded by
this gene
- No/reduced NK cell development
- No/reduced T cell development

Question 5

How is CGD (Chronic Granulomatous Disease) caused and how does this affect the immune system?

Answer 5

Mutations in genes that code for NADPH oxidase complex components:

Reduces phagocytic killing by neutrophils

Question 6

Non-genetic causes of immunodeficiency:

Answer 6

Aging, prematurity
Infection (HIV, measles)
Malignancy (Cancer)
Biochemical and nutritional disorders (malnutrition)

Question 7

Common upper respiratory tract complications:

Answer 7

Sinusitis
Otitis media
Laryngeal angioedema

Question 8

Common lower respiratory tract complications:

Answer 8

Bronchitis
Malignancies
Interstitial lung disease
Pneumonia

Question 9

Symptoms of X-SCID:

Answer 9

Persistent diarrhoea
Infections of all types
Unusual skin disease