primary immunodeficiency

Question 1

What is the cause of DiGeorge Syndrome?

Answer 1

Developmental failure of the third and fourth pharyngeal pouches due to a 22q11 microdeletion

Question 2

What are the key features of DiGeorge Syndrome?

Answer 2

T-cell deficiency (lack of thymus)
Hypocalcemia (lack of parathyroids)
Abnormalities of heart, great vessels, and face

Question 3

: What is the primary cause of Severe Combined Immunodeficiency (SCID)?

Answer 3

Defective cell-mediated and humoral immunity.

Question 4

What are the causes of SCID?

Answer 4

Cytokine receptor defects (needed for B and T cell proliferation and maturation).

Adenosine deaminase (ADA) deficiency (build-up of toxic substances affects lymphocytes).

MHC class II deficiency (needed for CD4+ helper T cell activation).

Question 5

What infections are individuals with SCID susceptible to?

Answer 5

Fungal, viral, bacterial, and protozoal infections, including opportunistic infections and live vaccines.

Question 6

What is the treatment for Severe Combined Immunodeficiency (SCID)?

Answer 6

Sterile isolation (“bubble baby”) and stem cell transplantation.

Question 7

What is the cause of X-linked Agammaglobulinemia?

Answer 7

Complete lack of immunoglobulin due to disordered B-cell maturation caused by a mutation in Bruton tyrosine kinase (X-linked).

Question 8

What is the age of onset and typical symptoms of X-linked Agammaglobulinemia?

Answer 8

Presents after 6 months of life with recurrent bacterial infections, enterovirus infections (e.g., polio, coxsackievirus), and Giardia lamblia infections.

Question 9

What role do maternal antibodies play in X-linked Agammaglobulinemia?

Answer 9

Maternal antibodies are protective during the first 6 months of life.

Question 10

What must be avoided in individuals with X-linked Agammaglobulinemia?

Answer 10

Live vaccines (e.g., polio).

Question 11

What is the cause of Common Variable Immunodeficiency (CVID)?

Answer 11

Low immunoglobulin due to B-cell or helper T-cell defects.

Question 12

What infections are individuals with Common Variable Immunodeficiency (CVID) at increased risk for?

Answer 12

Bacterial, enterovirus, and Giardia lamblia infections, usually in late childhood.

Question 13

What other health risks are associated with Common Variable Immunodeficiency (CVID)?

Answer 13

Increased risk for autoimmune disease and lymphoma.

Question 14

What is the most common immunoglobulin deficiency?

Answer 14

IgA deficiency.

Question 15

What are the key features of IgA Deficiency?

Answer 15

Low serum and mucosal IgA.

Increased risk for mucosal infections, especially viral.

Most patients are asymptomatic.

Question 16

What causes Hyper-IgM Syndrome?

Answer 16

Mutated CD40L (on helper T cells) or CD40 receptor (on B cells), preventing proper B-cell activation and cytokine production necessary for immunoglobulin class switching.

Question 17

What are the immunoglobulin levels in Hyper-IgM Syndrome?

Answer 17

Elevated IgM and low IgA, IgG, and IgE.

Question 18

What type of infections are common in Hyper-IgM Syndrome?

Answer 18

Recurrent pyogenic infections, especially at mucosal sites, due to poor opsonization.

Question 19

What are the key features of Wiskott-Aldrich Syndrome?

Answer 19

Thrombocytopenia, eczema, and recurrent infections (defective humoral and cellular immunity).

Bleeding is a major cause of death.

Question 20

What is the cause of Wiskott-Aldrich Syndrome?

Answer 20

Mutation in the WASP gene, X-linked inheritance.

Question 21

What infections are individuals with complement deficiencies at increased risk for?

Answer 21

Neisseria infections (e.g., N. gonorrhoeae and N. meningitidis) due to C5-C9 deficiencies.

Question 22

What is the result of C1 inhibitor deficiency?

Answer 22

Hereditary angioedema, characterized by edema of the skin (especially periorbital) and mucosal surfaces.