Primary Immunodeficiency (PI) is an umbrella term for over 350 genetic defects and disorders of the immune system recognized by the World Health Organization. Together they affect approximately 29,000 Canadians. Primary Immunodeficiency is not considered a rare disease as a category, but each individual form of PI is rare.
There are currently 5 names in this directory beginning with the letter I.
IgG Subclass Deficiency
The main immunoglobulin (Ig) in human blood is IgG. IgG is a combination of four subclasses: IgG1, IgG2, IgG3 and IgG4. When one or more of these subclasses is consistently low and total IgG is normal, then an individual has IgG Subclass Deficiency. IgG subclass deficiency is a controversial diagnosis and experts disagree about the findings of the condition.
Individuals with any IgG subclass deficiency occasionally have recurrent respiratory infections, primarily Streptococcus pneumoniae and Haemophilus Influenzae. These infections may not be as severe as they are for individuals with primary immunodeficiencies like Agammaglobulinemia or Common Variable Immunodeficiency (CVID). Treatments for persistent IgG Subclass Deficiency include antibiotics and immunoglobulin replacement therapy. Many children outgrow the deficiency as they age.
Credits: Immune Deficiency Foundation
Immunodeficiency with Centromeric Instability and Facial Anomalies
ICF syndrome is an inherited disorder passed down from both parents due to defects in the DNA methyl transferable gene DNMT3B. The disorder results in abnormal facial features, including large tongues (macroglossia). Individuals with ICF are susceptible to bacterial and opportunistic infections.
Early treatment is ideal for individuals with ICF, because immunoglobulin supplementation can help with the development of the disease. For those who have severe infections or fail to thrive (gain weight, grow), allogeneic stem cell transplantation is recommended.
Credits: Immune Deficiency Foundation
Immunodeficiency with Thymoma (Good’s Syndrome)
Immunodeficiency with Thymoma (aka. Good's Syndrome) is characterized by low immunoglobulins, along with a thymic tumor (thymoma). The condition is suspected when a thymic tumor is seen on a chest X-ray. Most patients with Good's Syndrome are adults with a history of recurrent infections. Removing the thymoma will not cure the immunodeficiency; however, may be an improvement for other symptoms.
IRAK4 Deficiency
IRAK4 Deficiency is an innate immune defect and inherited disorder. The condition leads to current pyogenic (pus-producing) bacterial infections. The infections are mostly caused by S. aureus, S. pneumoniae (pneumococcus) and Pseudomonas aeruginosa. These infections can be life-threatening when they occur during infancy. While the bacterial infections are recurring, individuals with the condition do not suffer from severe viral, fungal, or parasitic infections.
IRAK4 Deficiency has similar symptoms to the primary immunodeficiency MyD88 deficiency. Like with MyD88 Deficiency, the health of individuals with IRAK4 Deficiency improves with age. The IRAK4 Deficiency is rare and the estimated frequency of the condition is unknown.
Credits: Immune Deficiency Foundation, Genetics Home Reference