primary immunodeficiency Flashcards
What is the cause of DiGeorge Syndrome?
Developmental failure of the third and fourth pharyngeal pouches due to a 22q11 microdeletion
What are the key features of DiGeorge Syndrome?
T-cell deficiency (lack of thymus)
Hypocalcemia (lack of parathyroids)
Abnormalities of heart, great vessels, and face
: What is the primary cause of Severe Combined Immunodeficiency (SCID)?
Defective cell-mediated and humoral immunity.
What are the causes of SCID?
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).
What infections are individuals with SCID susceptible to?
Fungal, viral, bacterial, and protozoal infections, including opportunistic infections and live vaccines.
What is the treatment for Severe Combined Immunodeficiency (SCID)?
Sterile isolation (“bubble baby”) and stem cell transplantation.
What is the cause of X-linked Agammaglobulinemia?
Complete lack of immunoglobulin due to disordered B-cell maturation caused by a mutation in Bruton tyrosine kinase (X-linked).
What is the age of onset and typical symptoms of X-linked Agammaglobulinemia?
Presents after 6 months of life with recurrent bacterial infections, enterovirus infections (e.g., polio, coxsackievirus), and Giardia lamblia infections.
What role do maternal antibodies play in X-linked Agammaglobulinemia?
Maternal antibodies are protective during the first 6 months of life.
What must be avoided in individuals with X-linked Agammaglobulinemia?
Live vaccines (e.g., polio).
What is the cause of Common Variable Immunodeficiency (CVID)?
Low immunoglobulin due to B-cell or helper T-cell defects.
What infections are individuals with Common Variable Immunodeficiency (CVID) at increased risk for?
Bacterial, enterovirus, and Giardia lamblia infections, usually in late childhood.
What other health risks are associated with Common Variable Immunodeficiency (CVID)?
Increased risk for autoimmune disease and lymphoma.
What is the most common immunoglobulin deficiency?
IgA deficiency.
What are the key features of IgA Deficiency?
Low serum and mucosal IgA.
Increased risk for mucosal infections, especially viral.
Most patients are asymptomatic.
What causes Hyper-IgM Syndrome?
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.
What are the immunoglobulin levels in Hyper-IgM Syndrome?
Elevated IgM and low IgA, IgG, and IgE.
What type of infections are common in Hyper-IgM Syndrome?
Recurrent pyogenic infections, especially at mucosal sites, due to poor opsonization.
What are the key features of Wiskott-Aldrich Syndrome and what is the main cause of death ?
Thrombocytopenia, eczema, and recurrent infections (defective humoral and cellular immunity).
Bleeding is a major cause of death.
What is the cause of Wiskott-Aldrich Syndrome?
Mutation in the WASP gene, X-linked inheritance.
What infections are individuals with complement deficiencies at increased risk for?
Neisseria infections (e.g., N. gonorrhoeae and N. meningitidis) due to C5-C9 deficiencies.
What is the result of C1 inhibitor deficiency?
Hereditary angioedema, characterized by edema of the skin (especially periorbital) and mucosal surfaces.
