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What are PIDs?

Primary Immunodeficiencies

Primary immunodeficiencies, commonly referred to as inborn errors of immunity (IEI), are a class of more than 450 uncommon, chronic diseases in which a component of the immune system is absent or does not work properly. Anyone, regardless of age, gender, or race, can get these diseases because of hereditary genetic flaws.

While PIs differ, they all share one common feature: disruption of the body’s immune system. Because the most important function of the immune system is to protect against infection, people with PI commonly experience increased susceptibility to infection. The infections may be in the skin, sinuses, throat, ears, lungs, brain, or spinal cord, or in the urinary or intestinal tracts. Increased susceptibility to infection may show up as repeated infections, infections that won’t clear up, or unusually severe infections.

What are the symptoms?

What are other signs of Primary Immunodeficiencies?

Although being more vulnerable to infection than average is the most common symptom across PIs, there are other symptoms that can indicate you have a PI. These include a swollen spleen, liver, or lymph node, inflammation of blood vessels, and autoimmune symptoms like inflammatory bowel disease.

  • Frequent and recurrent pneumonia, bronchitis, sinus infections, ear infections, meningitis or skin infections
  • Inflammation and infection of internal organs
  • Blood disorders, such as low platelet count or anemia
  • Digestive problems, such as cramping, loss of appetite, nausea and diarrhea
  • Delayed growth and development
  • Autoimmune disorders, such as lupus, rheumatoid arthritis or type 1 diabetes
Main Generic Types of

Primary Immunodeficiency

There are more than 450 primary immunodeficiencies recognized by the International Union of Immunological Societies. Here are some of the most common disorders are listed.

Ataxia Telangiectasia
Rare inherited disorder that affects the nervous system, immune system, and other body systems.
Chronic Granulomatous Disease
A genetic disorder in which white blood cells called phagocytes are unable to kill certain types of bacteria and fungi.
Hyper IgM Syndrome
Characterized by decreased blood levels of immunoglobulin G (IgG) and normal or elevated levels of immunoglobulin M (IgM).
Primary Hemophagocytic LymphoHistiocytosis
An immune deficiency disorder where part of the immune system is missing or defective.
Autoimmune Lymphoproliferative Syndrome
An inherited disorder in which the body cannot properly regulate the number of immune system cells (lymphocytes).
Combined Variable Immunodeficiency
Characterized by low levels of protective antibodies and an increased risk of infections.
Hypogammaglobulinemia Syndrome
Disorder caused by low serum immunoglobulin or antibody levels.
Severe Combined Immunodeficiency
Group of rare disorders caused by mutations in different genes involved in the development and function of infection-fighting immune cells.
Severe Congenital Neutropenia
Selective decrease in circulating neutrophils, bone marrow maturation arrest at the promyelocyte stage, and occurrence of infections.
Hyper IgE Syndrome
Characterized by elevated serum IgE, rash and recurrent bacterial infections of the skin and lung.
Immunoglobulin A Deficiency
Characterized by undetectable serum IgA, a concomitant lack of secretory IgA, and normal levels of other immunoglobulins.
Bruton's Agammaglobulinemia
Characterized by the absence of mature B cells which in turn leads to severe antibody deficiency and recurrent infections.
Wiskott-Aldrich Syndrome
Keeps a child’s immune system from functioning properly and difficult for a child’s bone marrow to produce platelets.

4 Stages Of Testing For Primary Immunodeficiency

  • History and physical examination
  • FBC and differential
  • Quantitative Immunoglobulin levels IgG, IgM, IgA

Stage 01

  • Specific antibody responses (tetanus, diphtheria, pneumococcus)
  • Lymphocyte surface markers CD3/CD4/CD8/CD19/CD56
  • Total IgE

Stage 02

  • Lymphocyte proliferation studies (mitogen/antigen stimulation or skin delayed type hypersensitivity)
  • Neutrophil oxidation burst (if indicated)
  • Response to pneumococcal vaccine (for ages 2 years old and above)

Stage 03

  • Complement screening CH50, specific complement components, AH50
  • Enzyme activity measurements (e.g., adenosine deaminase, purine nucleoside phosphorylase)
  • Phagocyte studies (e.g., surface glycoproteins, mobility, phagocytosis)
  • Neo antigen response to test antibody production
  • Other surface molecules for detailed immunophenotype (e.g., memory B cells, T/NK cell subpopulations)
  • Specific protein levels
  • Other function receptor quantification
  • Genetic test

Stage 04

Types of Treatment for

Intravenous Immunoglobulin (IVIG) Replacement Therapy

  • IVIG is given through a vein by a healthcare professional every 3-4 weeks at a dose determined by the doctor.
  • Central catheters are not recommended due to the risk of infections and blood clots. Subcutaneous route can be used instead.
  • IVIG can be given in various settings, but self-infusion should be done with medical professional presence due to the risk of serious side effects.

Subcutaneous Immunoglobulin (SCIG) Replacement Therapy

  • SCIG is given under the skin at one or multiple sites, depending on the volume being infused.
  • Dose is calculated based on the interval between infusions, and it can be infused daily, weekly, or every two to four weeks.
  • Dosage is adjusted to minimize infections, and IgG levels are monitored to correlate with clinical outcomes.
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