Primary Immunodeficiency

Full interactive modules and 5 EMR cases covering XLA, CVID, SCID, DiGeorge, and CGD.

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MECHANISM MODULE
PID MechanismDx — Full Module
7 topics: XLA vs CVID, IgA/subclass deficiency, SCID/TREC, DiGeorge/22q11.2, CGD/DHR, complement deficiencies. 4 EMR cases linked. ABAI Domain 3.
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EMR CASE
X-Linked Agammaglobulinemia (XLA)
2-year-old male with 4th bacterial infection — septic arthritis, recurrent encapsulated bacteria since 6 months.
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EMR CASE
ADA-SCID — Newborn Screening
6-week-old detected pre-symptomatically by absent TRECs on newborn screening. HSCT pathway.
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EMR CASE
DiGeorge Syndrome — 22q11.2
Newborn with truncus arteriosus, hypocalcemia seizure, and cleft palate. Partial vs complete DiGeorge vaccine counseling.
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EMR CASE
Chronic Granulomatous Disease (CGD)
5-year-old with suppurative lymphadenitis, Aspergillus history, DHR test, IFN-γ initiation, and CGD colitis.

About Primary Immunodeficiency

Primary immunodeficiency disorders are rare genetic conditions where the immune system fails to develop or function properly from birth. These inherited disorders affect various components of the immune system including B cells, T cells, phagocytes, or complement proteins, leading to increased susceptibility to recurrent infections.

Pathophysiology

Primary immunodeficiencies result from genetic mutations that impair immune system development or function, affecting adaptive immunity (B and T cells), innate immunity (neutrophils, macrophages), or complement cascade. The defects can involve antibody production, cellular immunity, phagocytic function, or complement activation, creating specific patterns of immune vulnerability based on the affected pathway.

Clinical Reasoning

Diagnosis requires recognizing patterns of recurrent, severe, or unusual infections that begin early in life, often with specific pathogen susceptibilities based on the immune defect type. Clinical evaluation focuses on infection history, growth patterns, and family history, followed by immunologic testing including immunoglobulin levels, lymphocyte subsets, and functional assays to identify the specific immune pathway affected.

References

  1. Primary Immunodeficiency. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK551620/
  2. AAAAI Practice Parameter: Immunodeficiency. JACI 2015. https://doi.org/10.1016/j.jaci.2015.03.025
  3. Primary Immunodeficiency Guidelines. JACI: In Practice. https://doi.org/10.1016/j.jaip.2021.06.006
  4. Warning Signs of Primary Immunodeficiency. Jeffrey Modell Foundation. https://info4pi.org/
  5. Immune Deficiency Foundation Patient Resources. IDF. https://primaryimmune.org/

Related Topics

ImmunodeficiencyHIV/AIDS: Diagnosis & ManagementIVIG & SCIG: Immunoglobulin Replacement Therapy