Primary immunodeficiency Flashcards
What embryonic structures are maldeveloped in DiGeorge Syndrome?
3rd and 4th pharyngeal pouches
What deletion causes DiGeorge syndrome?
22q11 microdeletion
What are the clinical signs of DiGeorge syndrome?
CATCH 22
- Cardiac defects
- Abnormal facies
- Thymic aplasia
- Cleft palate
- Hypocalcemia - lack of parathyroid glands
T cell deficiency will leave a patient vulnerable to what kind of infections?
- Fungal
- Viral
What are the 3 eitiologies behind SCID (severe combined immunodeficiency)
- Cytokine receptor defects
- Adenosine deaminase deficiency
- MHC class II deficiency
Leads to defective cell-mediated and humoral immunity
What is adenosine deaminase?
- Why is this essential to lymphocytes
Enzyme necessary for deamination of adenosine and deoxyadenosine
- Build up of adenosine and deoxyadeonsine is toxic to lymphocytes
What vaccines should be avoided in SCID and X-linked agammaglobulinemia patients?
Live vaccines
- e.g polio
What is the treatment of SCID?
- Sterile isolation (bubble boy)
- Stem cell transplant
What is X-link agammaglobulinemia due to?
What enzyme is defective?
- Mutated Bruton tyrosine kinase
- Disordered B-cell maturation
- Naive B cells cannot mature to plasma cells -> no immunoglobulins
Where is the bruton tyrosine kinase (BTK) enzyme found?
X chromosome
- X-linked agammaglobulinemia
When does X-linked agammaglobulinemia present?
6 months after life
What infections become recurrent in X-linked agammaglobulinemia?
- Bacterial
- Enterovirus and Giardia (found on mucosa of GI tract - no IgA to protect)
What is common variable immunodeficiency (CVID) due to?
Low immunoglobulin due to B-cell or helper T-cell defects
What diseases are those with CVID at risk of?
- Bacterial, enterovirus and Giardia - usually late childhood
- Increased risk for autoimmune disease and lymphoma
What is the most common Ig deficiency?
IgA deficiency
- At risk for mucosal infections - especially viral
What GI disease has a high propensity of patients with IgA deficiency?
Celiac
What is Hyper-IgM syndrome due to (mutation)?
- Describe the eitiology
- Mutated CD40L or CD40 receptor
- 2nd signal cannot be delivered to helper T cells during B-cell activation
- Cytokines necessary for Ig class switching not produced
- Low IgA, IgG and IgE result in recurrent pyogenic infections, esopecialy at mucosal sites
What is the triad behind Wiskott-Aldrich Syndrome?
- Thrombocytopenia
- Eczema
- Recurrent infections (defective humoral and cellular immunity)
How is Wiskott-Aldrich Syndrome inherited?
X-linked
- WAS protein (WASP)
What infections are those with C5-C9 deficiency at risk of?
Neisseria (meningitis)
What will those with C1 inhibitor deficiency develop, what characteristic sign?
- Hereditary angioedema
- Characterised by edema of skin - periorbital edema
- Mucosal surfaces edema
